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 (
    108997, 97273, 108863, 108847, 108846, 
    110784, 108984, 97010, 97009, 97008, 
    109024, 110785, 108955, 98935, 108976, 
    108865, 108864, 109010, 108876, 108875
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00056

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
97008 25M 0
97009 25M 0
97010 25M 0
97273 25M 0
98935 25M 0
108846 25M 0
108847 25M 0
108863 25M 0
108864 25M 0
108865 25M 0
108875 25M 0
108876 25M 0
108955 25M 0
108976 25M 0
108984 25M 0
108997 25M 0
109010 25M 0
109024 25M 0
110784 25M 0
110785 25M 0