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 (
    87742, 87741, 87656, 87644, 87643, 87642, 
    87641, 87640, 87639, 87638, 87637, 
    87636, 87635, 87634, 87633, 87632, 
    87631, 87630, 87629, 87628
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00048

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
87628 1M 0
87629 1M 0
87630 1M 0
87631 1M 0
87632 1M 0
87633 1M 0
87634 1M 0
87635 1M 0
87636 1M 0
87637 1M 0
87638 1M 0
87639 1M 0
87640 1M 0
87641 1M 0
87642 1M 0
87643 1M 0
87644 1M 0
87656 1M 0
87741 1M 0
87742 1M 0