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.company_id = 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 = 940 
WHERE 
  cscart_products_categories.product_id IN (
    10705, 10195, 10670, 9457, 8862, 11485, 
    10960, 10172, 10201, 10945, 397, 10188
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00159

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_products_categories range PRIMARY,pt,product_id_idx,category_id_idx,product_category_idx,category_product_idx pt 3 146 Using index condition
1 SIMPLE product_position_source eq_ref PRIMARY,pt,product_id_idx,category_id_idx,product_category_idx,category_product_idx PRIMARY 6 const,mahm3t_cs443.cscart_products_categories.product_id 1
1 SIMPLE cscart_categories eq_ref PRIMARY,c_status,p_category_id,idx_category_id PRIMARY 3 mahm3t_cs443.cscart_products_categories.category_id 1 Using where

Result

product_id category_ids position
397 937,940,942,432M 0
8862 938,940,943,482M 0
9457 938,940,942,922M 0
10172 937,940,943,482M 0
10188 938,940,942,432M 0
10195 937,940,942,925M 0
10201 937,940,942,432M 0
10670 937,940,944,929M 0
10705 938,940,942,925M 0
10945 938,940,943,482M 0
10960 942,937,940,432M 0
11485 938,940,942,432M 0