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 = 25 
WHERE 
  cscart_products_categories.product_id IN (
    111706, 111705, 111704, 111703, 111702, 
    111701, 111700, 111699, 111698, 111697, 
    111696, 111695, 111694, 111693, 111692, 
    111691, 111690, 111902, 111843, 111684
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00062

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
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
111684 25M 0
111690 25M 0
111691 25M 0
111692 25M 0
111693 25M 0
111694 25M 0
111695 25M 0
111696 25M 0
111697 25M 0
111698 25M 0
111699 25M 0
111700 25M 0
111701 25M 0
111702 25M 0
111703 25M 0
111704 25M 0
111705 25M 0
111706 25M 0
111843 25M 0
111902 25M 0