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 (
    10529, 10528, 10527, 10526, 10525, 10524, 
    10522, 10495, 10494, 10493, 10492, 
    10491, 10490, 10489, 10488, 10487, 
    10486, 10485, 10483, 10482, 10481, 
    10480, 10479, 10478, 10477, 10476, 
    10475, 10474, 10473, 10472, 10471, 
    10470, 10469, 10468, 10467, 10466, 
    12582, 12583, 12584, 10465, 10464, 
    10463, 10462, 10461, 10460, 10459, 
    12581, 12699, 12698, 12697, 12696, 
    12695, 12694, 12693, 12692, 12691, 
    10447, 10448, 10449, 10450, 10451, 
    10452, 10453, 10454
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00081

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": 68,
      "filtered": 100,
      "index_condition": "cscart_products_categories.product_id in (10529,10528,10527,10526,10525,10524,10522,10495,10494,10493,10492,10491,10490,10489,10488,10487,10486,10485,10483,10482,10481,10480,10479,10478,10477,10476,10475,10474,10473,10472,10471,10470,10469,10468,10467,10466,12582,12583,12584,10465,10464,10463,10462,10461,10460,10459,12581,12699,12698,12697,12696,12695,12694,12693,12692,12691,10447,10448,10449,10450,10451,10452,10453,10454)"
    },
    "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')"
    }
  }
}