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 (
    10331, 10358, 10378, 10311, 10332, 10359, 
    10379, 10312, 10333, 10360, 10380, 
    10334, 10361, 10381, 10335, 10362, 
    10336, 10363, 10337, 10364, 10338, 
    10365, 10339, 10366, 10340, 10367, 
    10341, 10368, 10342, 12565, 10293, 
    10296, 10301, 10313, 10318, 10294, 
    10297, 10302, 10314, 10319, 12552, 
    12554, 10295, 10298, 10303, 10315, 
    10320, 10299, 10304, 10316, 10321, 
    10300, 10317, 10322, 12572, 12575, 
    12571, 12573, 10273, 10272, 10271, 
    10270, 10269, 10268
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00183

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": 71,
      "filtered": 100,
      "index_condition": "cscart_products_categories.product_id in (10331,10358,10378,10311,10332,10359,10379,10312,10333,10360,10380,10334,10361,10381,10335,10362,10336,10363,10337,10364,10338,10365,10339,10366,10340,10367,10341,10368,10342,12565,10293,10296,10301,10313,10318,10294,10297,10302,10314,10319,12552,12554,10295,10298,10303,10315,10320,10299,10304,10316,10321,10300,10317,10322,12572,12575,12571,12573,10273,10272,10271,10270,10269,10268)"
    },
    "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')"
    }
  }
}