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, 
  product_position_source.position AS position 
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') 
  LEFT JOIN cscart_products_categories AS product_position_source ON cscart_products_categories.product_id = product_position_source.product_id 
  AND product_position_source.category_id = 265 
WHERE 
  cscart_products_categories.product_id IN (
    9824, 9825, 9826, 9827, 9828, 9829, 9830, 
    10241, 10242, 10243, 10244, 10245, 
    10246, 10247, 10248, 10249, 10250, 
    10251, 10252, 10253, 10254, 10255, 
    10256, 10257, 10258, 10259, 10260, 
    10261, 10713, 10714, 10715, 10716, 
    10717, 10718, 10719, 10720, 10721, 
    10722, 10723, 10739, 10740, 10741, 
    10742, 10305, 10306, 10307, 10308, 
    10309, 10310, 10311, 10312, 12999, 
    13000, 13001, 13002, 13003, 13004, 
    13005, 13006, 13007, 13008, 13009, 
    13010, 13011
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00164

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": 64,
      "filtered": 100,
      "index_condition": "cscart_products_categories.product_id in (9824,9825,9826,9827,9828,9829,9830,10241,10242,10243,10244,10245,10246,10247,10248,10249,10250,10251,10252,10253,10254,10255,10256,10257,10258,10259,10260,10261,10713,10714,10715,10716,10717,10718,10719,10720,10721,10722,10723,10739,10740,10741,10742,10305,10306,10307,10308,10309,10310,10311,10312,12999,13000,13001,13002,13003,13004,13005,13006,13007,13008,13009,13010,13011)"
    },
    "table": {
      "table_name": "product_position_source",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY", "pt"],
      "key": "PRIMARY",
      "key_length": "6",
      "used_key_parts": ["category_id", "product_id"],
      "ref": [
        "const",
        "noframes_angrybeaver.cscart_products_categories.product_id"
      ],
      "rows": 1,
      "filtered": 100
    },
    "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')"
    }
  }
}