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 = 3 
  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 = 737 
WHERE 
  cscart_products_categories.product_id IN (
    430, 9470, 10705, 750, 10195, 426, 10670, 
    9457, 10157, 9938, 8862, 8860, 3322, 
    11485, 10960, 9845, 9853, 717, 9843, 
    10065, 10707, 478, 3325, 428, 3321, 
    10101, 10172, 8878, 514, 10070, 8295, 
    3315, 7353, 4939, 480, 3318, 10067, 
    9851, 3320, 9842, 10104, 10063, 407, 
    8861, 405, 10201, 3319, 9849
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00445

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 3 428 Using index condition
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
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

Result

product_id category_ids position
405 813,1005
407 813,998,1006
426 930,962,963,968
428 999,1001
430 927,961,963,967
478 814,1005
480 814,1006
514 808,813,814,998,1002
717 808,813,998,1005
750 927,962,963,967
3315 971
3318 808,1005
3319 808,1005
3320 808,1005
3321 814,1001
3322 808,813,998,1001
3325 808,1001
4939 1001,813,998
7353 1005,813,998
8295 808,813,814,1004,998,999,1000
8860 747,961,963,966
8861 747,961,963,967
8862 747,961,964,966
8878 747,962,963,966
9457 924,961,964,967
9470 927,961,963,969
9842 814,1001,1002
9843 814,1001
9845 1001,814
9849 814,1005
9851 814,1009
9853 814,1005
9938 971
10063 973
10065 973
10067 973
10070 999,1005
10101 973
10104 1009,813,998
10157 930,962,963,968
10172 747,962,964,966
10195 927,962,964,967
10201 746,962,964,967
10670 930,962,964,968
10705 927,961,964,967
10707 999,1001
10960 746,962,964,967
11485 746,961,967,964