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 (
    10102, 10643, 10178, 10177, 10606, 10644, 
    10101, 10175, 10100, 15962, 15961, 
    15960, 15959, 10094, 10093, 9813, 10097, 
    9760, 9759, 9934, 9933, 9932, 9931, 
    9936, 9947, 9953, 9952, 10074, 10096, 
    10075, 10602, 10087, 10130, 10603, 
    10135, 10134, 10139, 10138, 10137, 
    10141, 10143, 10142, 12628, 12627, 
    12629, 10095, 10195, 10194, 10193, 
    10190, 10496, 10198, 10202, 10201, 
    10200, 10227, 10226, 10651, 9945, 10642, 
    10601, 9727, 9728, 9729
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00181

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products_categories",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "pt"],
      "key": "pt",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 79,
      "filtered": 100,
      "index_condition": "cscart_products_categories.product_id in (10102,10643,10178,10177,10606,10644,10101,10175,10100,15962,15961,15960,15959,10094,10093,9813,10097,9760,9759,9934,9933,9932,9931,9936,9947,9953,9952,10074,10096,10075,10602,10087,10130,10603,10135,10134,10139,10138,10137,10141,10143,10142,12628,12627,12629,10095,10195,10194,10193,10190,10496,10198,10202,10201,10200,10227,10226,10651,9945,10642,10601,9727,9728,9729)"
    },
    "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": ["noframes_angrybeaver.cscart_products_categories.category_id"],
      "rows": 1,
      "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')"
    }
  }
}