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 = 4 
WHERE 
  cscart_products_categories.product_id IN (
    107397, 107396, 107395, 107394, 107393, 
    107392, 107391, 107381, 107675, 107493, 
    107492, 107491, 107729, 107728, 107555, 
    107390, 107389, 107388, 107387, 107280
  ) 
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 28 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
107280 29,6M
107381 4M 0
107387 4M 0
107388 4M 0
107389 4M 0
107390 4M 0
107391 4M 0
107392 29,4M 0
107393 29,4M 0
107394 29,4M 0
107395 29,4M 0
107396 4M 0
107397 4M 0
107491 4M 0
107492 29,4M 0
107493 4M 0
107555 4M 0
107675 4M 0
107728 29,4M 0
107729 29,4M 0