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 (
    10657, 12619, 12620, 12593, 12595, 12585, 
    12587, 12623, 13091, 12588, 12590, 
    12591, 12592, 10497, 10498, 10499, 
    10500, 10501, 10502, 10503, 10504, 
    10505, 10506, 10507, 10508, 10509, 
    10510, 10511, 10512, 10513, 10514, 
    10515, 10516, 10517, 10518, 10519, 
    10520, 10521, 10641, 10640, 10639, 
    10638, 10637, 10636, 10635, 10634, 
    10633, 10632, 10631, 10630, 10629, 
    10628, 10627, 10626, 10625, 10624, 
    10623, 10622, 10621, 10620, 10619, 
    10618, 10617, 10616
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00140

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": 76,
      "filtered": 100,
      "index_condition": "cscart_products_categories.product_id in (10657,12619,12620,12593,12595,12585,12587,12623,13091,12588,12590,12591,12592,10497,10498,10499,10500,10501,10502,10503,10504,10505,10506,10507,10508,10509,10510,10511,10512,10513,10514,10515,10516,10517,10518,10519,10520,10521,10641,10640,10639,10638,10637,10636,10635,10634,10633,10632,10631,10630,10629,10628,10627,10626,10625,10624,10623,10622,10621,10620,10619,10618,10617,10616)"
    },
    "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')"
    }
  }
}