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 
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') 
WHERE 
  cscart_products_categories.product_id IN (
    3826, 3660, 3649, 3733, 3740, 3743, 3944, 
    3741, 3811, 3441, 3653, 3946, 3768, 
    3734, 3821, 3747, 3641, 3952, 3738, 
    3435, 3798, 3443, 3730, 3737, 3638, 
    3655, 3729, 3658, 3851, 3668, 3942, 
    3732, 3448, 3702, 3728, 3852, 3850, 
    3731, 3769, 3642, 3745, 3943, 3623, 
    3670, 3684, 3645, 3437, 3637, 3682, 
    3767, 3950, 3644, 3659, 3766, 3864, 
    3940, 3436, 3739, 3444, 3785, 3442, 
    3787, 3945, 3438, 3770, 3865, 3447, 
    3793, 3450, 3772, 3795, 3788, 3439, 
    3446, 3687, 3860, 3794, 3858, 3869, 
    3948, 3449, 3941, 3871, 3786, 3853, 
    3857, 3863, 3867, 3951, 3862, 3854, 
    3949, 3727, 3699, 3881, 3855, 3859
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00362

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "236.26"
    },
    "grouping_operation": {
      "using_filesort": false,
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "range",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "pt",
            "used_key_parts": [
              "product_id"
            ],
            "key_length": "3",
            "rows_examined_per_scan": 265,
            "rows_produced_per_join": 265,
            "filtered": "100.00",
            "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_products_categories`.`product_id` in (3826,3660,3649,3733,3740,3743,3944,3741,3811,3441,3653,3946,3768,3734,3821,3747,3641,3952,3738,3435,3798,3443,3730,3737,3638,3655,3729,3658,3851,3668,3942,3732,3448,3702,3728,3852,3850,3731,3769,3642,3745,3943,3623,3670,3684,3645,3437,3637,3682,3767,3950,3644,3659,3766,3864,3940,3436,3739,3444,3785,3442,3787,3945,3438,3770,3865,3447,3793,3450,3772,3795,3788,3439,3446,3687,3860,3794,3858,3869,3948,3449,3941,3871,3786,3853,3857,3863,3867,3951,3862,3854,3949,3727,3699,3881,3855,3859))",
            "cost_info": {
              "read_cost": "117.01",
              "eval_cost": "26.50",
              "prefix_cost": "143.51",
              "data_read_per_join": "4K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "softwarepirmam_hewadelivard_cscart_4.cscart_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 13,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "66.25",
              "eval_cost": "1.33",
              "prefix_cost": "236.26",
              "data_read_per_join": "41K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`storefront_id` in (0,1)) and ((`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`usergroup_ids`))) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`status` in ('A','H')))"
          }
        }
      ]
    }
  }
}