SELECT 
  pfv.feature_id, 
  pfv.product_id, 
  pfv.variant_id, 
  fv.position, 
  fvd.variant 
FROM 
  cscart_product_features_values AS pfv 
  INNER JOIN cscart_product_feature_variants AS fv ON pfv.feature_id = fv.feature_id 
  AND pfv.variant_id = fv.variant_id 
  INNER JOIN cscart_product_feature_variant_descriptions AS fvd ON pfv.variant_id = fvd.variant_id 
  AND fvd.lang_code = 'ar' 
WHERE 
  pfv.feature_id IN (656) 
  AND pfv.product_id IN (
    3834, 3215, 3213, 3552, 3836, 3556, 3370, 
    3377, 3373, 3593, 3831, 3404, 3366, 
    3222, 3522, 3401, 3876, 3559, 3922, 
    3812, 3309, 3590, 3351, 3532, 3546, 
    3548, 3398, 3525
  ) 
  AND pfv.lang_code = 'ar'

Query time 0.00175

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "16.42"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "fl",
            "variant_id",
            "lang_code",
            "product_id",
            "fpl",
            "idx_product_feature_variant_id"
          ],
          "key": "idx_product_feature_variant_id",
          "used_key_parts": [
            "product_id",
            "feature_id",
            "lang_code"
          ],
          "key_length": "12",
          "rows_examined_per_scan": 28,
          "rows_produced_per_join": 28,
          "filtered": "100.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "3.33",
            "eval_cost": "2.80",
            "prefix_cost": "6.13",
            "data_read_per_join": "21K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ],
          "attached_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`pfv`.`feature_id` = 656) and (`softwarepirmam_hewadelivard_cscart_4`.`pfv`.`product_id` in (3834,3215,3213,3552,3836,3556,3370,3377,3373,3593,3831,3404,3366,3222,3522,3401,3876,3559,3922,3812,3309,3590,3351,3532,3546,3548,3398,3525)) and (`softwarepirmam_hewadelivard_cscart_4`.`pfv`.`lang_code` = 'ar'))"
        }
      },
      {
        "table": {
          "table_name": "fv",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY",
            "feature_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "ref": [
            "softwarepirmam_hewadelivard_cscart_4.pfv.variant_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 1,
          "filtered": "5.00",
          "cost_info": {
            "read_cost": "7.00",
            "eval_cost": "0.14",
            "prefix_cost": "15.93",
            "data_read_per_join": "1K"
          },
          "used_columns": [
            "variant_id",
            "feature_id",
            "position"
          ],
          "attached_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`fv`.`feature_id` = 656)"
        }
      },
      {
        "table": {
          "table_name": "fvd",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "softwarepirmam_hewadelivard_cscart_4.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 1,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "0.35",
            "eval_cost": "0.14",
            "prefix_cost": "16.42",
            "data_read_per_join": "4K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}