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 = 6 
WHERE 
  cscart_products_categories.product_id IN (
    97918, 97916, 97215, 97911, 97900, 97899, 
    97896, 97757, 97670, 97165, 97164, 
    97106, 92927, 96739, 97748, 97747, 
    97746, 92926, 97705, 97704
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00064

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
92926 6M 0
92927 6M 0
96739 6M 0
97106 6M 0
97164 6M 0
97165 6M 0
97215 6M 0
97670 6M 0
97704 6M 0
97705 6M 0
97746 6M 0
97747 6M 0
97748 6M 0
97757 6M 0
97896 6M 0
97899 6M 0
97900 6M 0
97911 6M 0
97916 6M 0
97918 6M 0