SELECT 
  f.feature_id, 
  f.purpose, 
  p.product_id, 
  p.parent_product_id, 
  g.id, 
  g.code 
FROM 
  cscart_product_variation_group_features AS f 
  INNER JOIN cscart_product_variation_groups AS g ON f.group_id = g.id 
  INNER JOIN cscart_product_variation_group_products AS p ON f.group_id = p.group_id 
WHERE 
  p.product_id IN (
    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, 3793, 3447, 3450, 3772, 3795, 
    3788, 3439, 3446, 3687, 3860, 3794, 
    3858, 3869, 3948
  )

Query time 0.00335

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "56.01"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "p",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "product_id"
          ],
          "key_length": "3",
          "rows_examined_per_scan": 40,
          "rows_produced_per_join": 40,
          "filtered": "100.00",
          "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`p`.`product_id` in (3745,3943,3623,3670,3684,3645,3437,3637,3682,3767,3950,3644,3659,3766,3864,3940,3436,3739,3444,3785,3442,3787,3945,3438,3770,3865,3793,3447,3450,3772,3795,3788,3439,3446,3687,3860,3794,3858,3869,3948))",
          "cost_info": {
            "read_cost": "24.01",
            "eval_cost": "4.00",
            "prefix_cost": "28.01",
            "data_read_per_join": "640"
          },
          "used_columns": [
            "product_id",
            "parent_product_id",
            "group_id"
          ]
        }
      },
      {
        "table": {
          "table_name": "g",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "id"
          ],
          "key_length": "3",
          "ref": [
            "softwarepirmam_hewadelivard_cscart_4.p.group_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 40,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "10.00",
            "eval_cost": "4.00",
            "prefix_cost": "42.01",
            "data_read_per_join": "15K"
          },
          "used_columns": [
            "id",
            "code"
          ]
        }
      },
      {
        "table": {
          "table_name": "f",
          "access_type": "ref",
          "possible_keys": [
            "idx_group_id"
          ],
          "key": "idx_group_id",
          "used_key_parts": [
            "group_id"
          ],
          "key_length": "3",
          "ref": [
            "softwarepirmam_hewadelivard_cscart_4.p.group_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 40,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "10.00",
            "eval_cost": "4.00",
            "prefix_cost": "56.01",
            "data_read_per_join": "4K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      }
    ]
  }
}