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 = 280 
WHERE 
  cscart_products_categories.product_id IN (
    9881, 9896, 9892, 10481, 9876, 10474, 
    10491, 10489, 10471, 9880, 10472, 9885, 
    10488, 9897, 9895, 10467, 9900, 10470, 
    10466, 10477, 9889, 10475, 9890, 10483, 
    10495, 10490, 10469, 9877, 9894, 9891, 
    10480, 9893, 9878, 9886, 9882, 9888, 
    10482, 9776, 9777, 9781, 9775, 9778, 
    9779, 9780, 9782, 9790, 9787, 9791, 
    9792, 9795, 9784, 9785, 9783, 9786, 
    9788, 13031, 13032, 13033, 13034, 13035, 
    13036, 13037, 13038, 13039, 13040, 
    13041, 13042, 13043, 13044, 10840, 
    10841, 10842, 10843, 10844, 10845, 
    10846, 10847, 13152
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00873

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": 78,
      "filtered": 100,
      "index_condition": "cscart_products_categories.product_id in (9881,9896,9892,10481,9876,10474,10491,10489,10471,9880,10472,9885,10488,9897,9895,10467,9900,10470,10466,10477,9889,10475,9890,10483,10495,10490,10469,9877,9894,9891,10480,9893,9878,9886,9882,9888,10482,9776,9777,9781,9775,9778,9779,9780,9782,9790,9787,9791,9792,9795,9784,9785,9783,9786,9788,13031,13032,13033,13034,13035,13036,13037,13038,13039,13040,13041,13042,13043,13044,10840,10841,10842,10843,10844,10845,10846,10847,13152)"
    },
    "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')"
    }
  }
}