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 = 1 
WHERE 
  cscart_products_categories.product_id IN (
    74996, 75157, 74620, 74619, 74618, 74617, 
    74616, 74615, 74614, 74613, 74612, 
    74611, 74870, 74993, 74918, 74515, 
    74513, 74512, 74898, 74465
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00055

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_products_categories range PRIMARY,pt pt 3 22 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
74465 1M 0
74512 28,1M 0
74513 1M 0
74515 28,1M 0
74611 1M 0
74612 1M 0
74613 1M 0
74614 1M 0
74615 1M 0
74616 1M 0
74617 1M 0
74618 1M 0
74619 1M 0
74620 1M 0
74870 1M 0
74898 1M 0
74918 1M 0
74993 1M 0
74996 1M 0
75157 1M 0