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 = 4 
WHERE 
  cscart_products_categories.product_id IN (
    94716, 94710, 94709, 94301, 94300, 94058, 
    93757, 94188, 93728, 93727, 93726, 
    93725, 93724, 93723, 93722, 93721, 
    93720, 93719, 93718, 93717
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00113

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_products_categories range PRIMARY,pt pt 3 25 Using where; Using index
1 SIMPLE cscart_categories eq_ref PRIMARY,c_status,p_category_id PRIMARY 3 toolboxdigitalshop_dev.cscart_products_categories.category_id 1 Using where
1 SIMPLE product_position_source eq_ref PRIMARY,pt PRIMARY 6 const,toolboxdigitalshop_dev.cscart_products_categories.product_id 1

Result

product_id category_ids position
93717 4M 0
93718 4M 0
93719 4M 0
93720 4M 0
93721 4M 0
93722 4M 0
93723 29,4M 0
93724 29,4M 0
93725 29,4M 0
93726 4M 0
93727 29,4M 0
93728 4M 0
93757 4M 0
94058 4M 0
94188 29,4M 0
94300 4M 0
94301 4M 0
94709 4M 0
94710 4M 0
94716 4M 0