SELECT 
  q_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      q_products_categories.link_type = "M", 
      CONCAT(
        q_products_categories.category_id, 
        "M"
      ), 
      q_products_categories.category_id
    )
  ) AS category_ids 
FROM 
  q_products_categories 
  INNER JOIN q_categories ON q_categories.category_id = q_products_categories.category_id 
  AND (
    q_categories.usergroup_ids = '' 
    OR FIND_IN_SET(0, q_categories.usergroup_ids) 
    OR FIND_IN_SET(1, q_categories.usergroup_ids)
  ) 
  AND q_categories.status IN ('A', 'H') 
WHERE 
  q_products_categories.product_id IN (
    32849, 32850, 32851, 32852, 32853, 32854, 
    32855, 32856, 32857, 32858, 32859, 
    32860, 32861, 32862, 32863, 32864, 
    32865, 32866, 32867, 32868, 32869, 
    32870, 32871, 32872, 32873, 32874, 
    32875, 32876, 32877, 32878, 32879, 
    32880
  ) 
GROUP BY 
  q_products_categories.product_id

Query time 0.00085

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "175.01"
    },
    "grouping_operation": {
      "using_filesort": false,
      "nested_loop": [
        {
          "table": {
            "table_name": "q_products_categories",
            "access_type": "range",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "pt",
            "used_key_parts": [
              "product_id"
            ],
            "key_length": "3",
            "rows_examined_per_scan": 55,
            "rows_produced_per_join": 55,
            "filtered": "100.00",
            "index_condition": "(`portal`.`q_products_categories`.`product_id` in (32849,32850,32851,32852,32853,32854,32855,32856,32857,32858,32859,32860,32861,32862,32863,32864,32865,32866,32867,32868,32869,32870,32871,32872,32873,32874,32875,32876,32877,32878,32879,32880))",
            "cost_info": {
              "read_cost": "98.01",
              "eval_cost": "11.00",
              "prefix_cost": "109.01",
              "data_read_per_join": "880"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "table": {
            "table_name": "q_categories",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "portal.q_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 11,
            "filtered": "20.00",
            "cost_info": {
              "read_cost": "55.00",
              "eval_cost": "2.20",
              "prefix_cost": "175.01",
              "data_read_per_join": "29K"
            },
            "used_columns": [
              "category_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "(((`portal`.`q_categories`.`usergroup_ids` = '') or find_in_set(0,`portal`.`q_categories`.`usergroup_ids`) or find_in_set(1,`portal`.`q_categories`.`usergroup_ids`)) and (`portal`.`q_categories`.`status` in ('A','H')))"
          }
        }
      ]
    }
  }
}