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 (
    68534, 68533, 68459, 68363, 68362, 68360, 
    68358, 68357, 68135, 68065, 68064, 
    67902, 67896, 67685, 67684, 66983, 
    68359, 67955, 68319, 68312, 67848, 
    67845, 67839, 67686, 67683, 66841, 
    66840, 66839, 67958, 68200, 67770, 
    67769, 67768, 67767, 67766, 67765, 
    67764, 67763, 67762, 67761
  ) 
GROUP BY 
  cscart_products_categories.product_id