SELECT 
  q_discussion.object_id AS product_id, 
  AVG(
    q_discussion_rating.rating_value
  ) AS average_rating, 
  q_discussion.type AS discussion_type, 
  q_discussion.thread_id AS discussion_thread_id 
FROM 
  q_discussion 
  LEFT JOIN q_discussion_posts ON q_discussion_posts.thread_id = q_discussion.thread_id 
  AND q_discussion_posts.status = "A" 
  LEFT JOIN q_discussion_rating ON q_discussion.thread_id = q_discussion_rating.thread_id 
  AND q_discussion_rating.post_id = q_discussion_posts.post_id 
  AND q_discussion_rating.rating_value != 0 
WHERE 
  q_discussion.object_id IN (
    37513, 
    37514, 
    37515, 
    37516, 
    37520, 
    37521, 
    37522, 
    37523, 
    37524, 
    37525, 
    37526, 
    37527, 
    37528, 
    37529, 
    37530, 
    37531, 
    37532, 
    37533, 
    37534, 
    37535, 
    37536, 
    37537, 
    37538, 
    37539, 
    37540, 
    37541, 
    37542, 
    37543, 
    37544, 
    37545, 
    37546, 
    37547, 
    37548, 
    37549, 
    37550, 
    37551, 
    37552, 
    37553, 
    37554, 
    37555, 
    37557, 
    37558, 
    37559, 
    37560, 
    37561, 
    37562, 
    37563, 
    37820, 
    37821, 
    37822, 
    37823, 
    37824, 
    37825, 
    37826, 
    37827, 
    37828, 
    37829, 
    37830, 
    37831, 
    37832, 
    37833, 
    37834, 
    37835, 
    37836, 
    37837, 
    37838, 
    37839, 
    37840, 
    37841, 
    37842, 
    37843, 
    37844, 
    37845, 
    37846, 
    37847, 
    37848, 
    37849, 
    37850, 
    37851, 
    37852, 
    37853, 
    37854, 
    37855, 
    37856, 
    37858, 
    37859, 
    37860, 
    37861, 
    37862, 
    37863, 
    37864, 
    37865, 
    37866, 
    37867, 
    37868, 
    37869, 
    37870, 
    37871, 
    37872, 
    37873, 
    37874, 
    37875, 
    37877, 
    37878, 
    37879, 
    37880, 
    37881, 
    37882, 
    37883, 
    37884, 
    37885, 
    37886, 
    37887, 
    37888, 
    37889, 
    37890, 
    37891, 
    37892, 
    37893, 
    37894, 
    37895, 
    37896, 
    37897, 
    38150, 
    38151, 
    38152, 
    38155, 
    38156
  ) 
  AND q_discussion.object_type = "P" 
GROUP BY 
  q_discussion.object_id

Query time 0.00086

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "921.61"
    },
    "grouping_operation": {
      "using_filesort": false,
      "nested_loop": [
        {
          "table": {
            "table_name": "q_discussion",
            "access_type": "range",
            "possible_keys": [
              "object_id"
            ],
            "key": "object_id",
            "used_key_parts": [
              "object_id",
              "object_type"
            ],
            "key_length": "6",
            "rows_examined_per_scan": 128,
            "rows_produced_per_join": 128,
            "filtered": "100.00",
            "index_condition": "((`portal`.`q_discussion`.`object_id` in (37513,37514,37515,37516,37520,37521,37522,37523,37524,37525,37526,37527,37528,37529,37530,37531,37532,37533,37534,37535,37536,37537,37538,37539,37540,37541,37542,37543,37544,37545,37546,37547,37548,37549,37550,37551,37552,37553,37554,37555,37557,37558,37559,37560,37561,37562,37563,37820,37821,37822,37823,37824,37825,37826,37827,37828,37829,37830,37831,37832,37833,37834,37835,37836,37837,37838,37839,37840,37841,37842,37843,37844,37845,37846,37847,37848,37849,37850,37851,37852,37853,37854,37855,37856,37858,37859,37860,37861,37862,37863,37864,37865,37866,37867,37868,37869,37870,37871,37872,37873,37874,37875,37877,37878,37879,37880,37881,37882,37883,37884,37885,37886,37887,37888,37889,37890,37891,37892,37893,37894,37895,37896,37897,38150,38151,38152,38155,38156)) and (`portal`.`q_discussion`.`object_type` = 'P'))",
            "cost_info": {
              "read_cost": "281.61",
              "eval_cost": "25.60",
              "prefix_cost": "307.21",
              "data_read_per_join": "2K"
            },
            "used_columns": [
              "thread_id",
              "object_id",
              "object_type",
              "type"
            ]
          }
        },
        {
          "table": {
            "table_name": "q_discussion_posts",
            "access_type": "ref",
            "possible_keys": [
              "thread_id",
              "thread_id_2"
            ],
            "key": "thread_id",
            "used_key_parts": [
              "thread_id"
            ],
            "key_length": "3",
            "ref": [
              "portal.q_discussion.thread_id"
            ],
            "rows_examined_per_scan": 2,
            "rows_produced_per_join": 256,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "256.00",
              "eval_cost": "51.20",
              "prefix_cost": "614.41",
              "data_read_per_join": "112K"
            },
            "used_columns": [
              "post_id",
              "thread_id",
              "status"
            ],
            "attached_condition": "<if>(is_not_null_compl(q_discussion_posts), (`portal`.`q_discussion_posts`.`status` = 'A'), true)"
          }
        },
        {
          "table": {
            "table_name": "q_discussion_rating",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "thread_id"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "post_id"
            ],
            "key_length": "3",
            "ref": [
              "portal.q_discussion_posts.post_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 256,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "256.00",
              "eval_cost": "51.20",
              "prefix_cost": "921.61",
              "data_read_per_join": "4K"
            },
            "used_columns": [
              "rating_value",
              "post_id",
              "thread_id"
            ],
            "attached_condition": "<if>(is_not_null_compl(q_discussion_rating), ((`portal`.`q_discussion_rating`.`thread_id` = `portal`.`q_discussion`.`thread_id`) and (`portal`.`q_discussion_rating`.`rating_value` <> 0)), true)"
          }
        }
      ]
    }
  }
}