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 (
    30864, 30865, 30866, 30867, 30868, 30869, 
    30870, 30871, 30872, 30873, 30874, 
    30875, 30876, 30877, 30878, 30879, 
    30880, 30881, 30882, 30883, 30884, 
    30885, 30886, 30887, 30888, 30889, 
    30890, 30891, 30892, 30893, 30894, 
    30895
  ) 
GROUP BY 
  q_products_categories.product_id

Query time 0.00358

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "125.61"
    },
    "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": 36,
            "rows_produced_per_join": 36,
            "filtered": "100.00",
            "index_condition": "(`portal`.`q_products_categories`.`product_id` in (30864,30865,30866,30867,30868,30869,30870,30871,30872,30873,30874,30875,30876,30877,30878,30879,30880,30881,30882,30883,30884,30885,30886,30887,30888,30889,30890,30891,30892,30893,30894,30895))",
            "cost_info": {
              "read_cost": "75.21",
              "eval_cost": "7.20",
              "prefix_cost": "82.41",
              "data_read_per_join": "576"
            },
            "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": 7,
            "filtered": "20.00",
            "cost_info": {
              "read_cost": "36.00",
              "eval_cost": "1.44",
              "prefix_cost": "125.61",
              "data_read_per_join": "19K"
            },
            "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')))"
          }
        }
      ]
    }
  }
}