SELECT 
  cscart_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      cscart_products_categories.link_type = "M", 
      CONCAT(
        cscart_products_categories.category_id, 
        "M"
      ), 
      cscart_products_categories.category_id
    )
  ) AS category_ids 
FROM 
  cscart_products_categories 
  INNER JOIN cscart_categories ON cscart_categories.category_id = cscart_products_categories.category_id 
  AND cscart_categories.storefront_id IN (0, 1) 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
WHERE 
  cscart_products_categories.product_id IN (
    13861, 13862, 13863, 13864, 13865, 13876, 
    13877, 13878, 13879, 13880, 13881, 
    13882, 13899, 13900, 13901, 13902, 
    13903, 13913, 13914, 13915, 13919, 
    13920, 13947, 13948, 13949, 13963, 
    13964, 13965, 13966, 13967, 13968, 
    13971, 13972, 13973
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00062

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.091019108,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_products_categories",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "pt"],
          "key": "pt",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "loops": 1,
          "rows": 34,
          "cost": 0.03552529,
          "filtered": 100,
          "attached_condition": "cscart_products_categories.product_id in (13861,13862,13863,13864,13865,13876,13877,13878,13879,13880,13881,13882,13899,13900,13901,13902,13903,13913,13914,13915,13919,13920,13947,13948,13949,13963,13964,13965,13966,13967,13968,13971,13972,13973)",
          "using_index": true
        }
      },
      {
        "table": {
          "table_name": "cscart_categories",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "c_status", "p_category_id"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["category_id"],
          "ref": ["u508912950_dev_2025.cscart_products_categories.category_id"],
          "loops": 34,
          "rows": 1,
          "cost": 0.03368776,
          "filtered": 100,
          "attached_condition": "cscart_categories.storefront_id in (0,1) and (cscart_categories.usergroup_ids = '' or find_in_set(0,cscart_categories.usergroup_ids) or find_in_set(1,cscart_categories.usergroup_ids)) and cscart_categories.`status` in ('A','H')"
        }
      }
    ]
  }
}