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 = 1 
WHERE 
  cscart_products_categories.product_id IN (
    14819, 14818, 39047, 14808, 14807, 23244, 
    23237, 14795, 14720, 14713, 14730, 
    14728, 14726, 14723, 14722, 14787, 
    14701, 76378, 76377, 14677, 14663, 
    14662, 14661, 14660, 14659, 14658, 
    14657, 14656, 14654, 14653, 14652, 
    14651, 14649, 14648, 14647, 14646, 
    14645, 14644, 14643, 14642
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00077

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_products_categories range PRIMARY,pt pt 3 40 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
14642 1M 0
14643 1M 0
14644 1M 0
14645 1M 0
14646 1M 0
14647 1M 0
14648 1M 0
14649 1M 0
14651 1M 0
14652 1M 0
14653 1M 0
14654 1M 0
14656 1M 0
14657 1M 0
14658 1M 0
14659 1M 0
14660 1M 0
14661 1M 0
14662 1M 0
14663 1M 0
14677 1M 0
14701 1M 0
14713 1M 0
14720 1M 0
14722 1M 0
14723 1M 0
14726 1M 0
14728 1M 0
14730 1M 0
14787 1M 0
14795 1M 0
14807 1M 0
14808 1M 0
14818 1M 0
14819 1M 0
23237 1M 0
23244 1M 0
39047 1M 0
76377 1M 0
76378 1M 0