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 
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') 
WHERE 
  cscart_products_categories.product_id IN (
    47803, 47802, 47801, 47800, 47799, 47798, 
    47797, 47796, 47795, 47794, 47793, 
    47792, 47791, 47790, 47789, 47788, 
    47787, 47786, 47785, 47784
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00089

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_products_categories range PRIMARY,pt pt 3 20 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

Result

product_id category_ids
47784 22M
47785 22M
47786 22M
47787 22M
47788 22M
47789 22M
47790 22M
47791 22M
47792 22M
47793 22M
47794 22M
47795 22M
47796 22M
47797 22M
47798 22M
47799 22M
47800 22M
47801 22M
47802 22M
47803 22M