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 = 286 
WHERE 
  cscart_products_categories.product_id IN (
    10734, 10735, 10736, 10737, 10738, 10668, 
    10669, 10670, 10671, 10672, 10673, 
    10674, 10675, 10676, 10677, 10678, 
    10679, 10680, 10681, 10682, 10683, 
    10684, 10685, 10686, 10607, 10608, 
    10609, 10610, 10611, 10612, 10613, 
    10614, 10615, 10616, 10617, 10618, 
    10619, 10620, 10621, 10622, 10623, 
    10624, 9814, 9815, 9816, 9817, 9818, 
    15732, 9820, 9821, 9822, 9823, 9824, 
    9825, 9826, 9827, 9828, 9829, 9830, 
    10241, 10242, 10243, 10244, 10245
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00531

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": 67,
      "filtered": 100,
      "index_condition": "cscart_products_categories.product_id in (10734,10735,10736,10737,10738,10668,10669,10670,10671,10672,10673,10674,10675,10676,10677,10678,10679,10680,10681,10682,10683,10684,10685,10686,10607,10608,10609,10610,10611,10612,10613,10614,10615,10616,10617,10618,10619,10620,10621,10622,10623,10624,9814,9815,9816,9817,9818,15732,9820,9821,9822,9823,9824,9825,9826,9827,9828,9829,9830,10241,10242,10243,10244,10245)"
    },
    "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')"
    }
  }
}