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 = 283 
WHERE 
  cscart_products_categories.product_id IN (
    10785, 10786, 10787, 10788, 10789, 10790, 
    10791, 10767, 10768, 10769, 10770, 
    10771, 10772, 10773, 10774, 10775, 
    10776, 10777, 12944, 12985, 12986, 
    12987, 12988, 12989, 12990, 12991, 
    12992, 12993, 12994, 10063, 10052, 
    10072, 10046, 10059, 10064, 10057, 
    10048, 10062, 10070, 10058, 10045, 
    10054, 10047, 10071, 10067, 10051, 
    10060, 10055, 10043, 10068, 10065, 
    10061, 10050, 10056, 10044, 10069, 
    10066, 10024, 10025, 10026, 10027, 
    10028, 10029, 10030
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00105

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 (10785,10786,10787,10788,10789,10790,10791,10767,10768,10769,10770,10771,10772,10773,10774,10775,10776,10777,12944,12985,12986,12987,12988,12989,12990,12991,12992,12993,12994,10063,10052,10072,10046,10059,10064,10057,10048,10062,10070,10058,10045,10054,10047,10071,10067,10051,10060,10055,10043,10068,10065,10061,10050,10056,10044,10069,10066,10024,10025,10026,10027,10028,10029,10030)"
    },
    "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')"
    }
  }
}