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 = 'en' 
WHERE 
  pfv.feature_id IN (656, 658) 
  AND pfv.product_id IN (
    908, 3090, 2752, 1143, 2559, 2822, 2253, 
    2751, 2255, 2927, 2729, 3140, 1542, 
    3026, 853, 1540, 1544, 2251, 2252, 2254, 
    2869, 2877, 2788, 2795, 2936, 2792, 
    3021, 3373, 3011, 2760, 3060, 2880, 
    3014, 3404, 3366, 3160, 3023, 3099, 
    2800, 2860, 2775, 2767, 2562, 3548, 
    5151, 2786, 5126, 5133, 8703, 7873, 
    7871, 7874, 10455
  ) 
  AND pfv.lang_code = 'en'

Query time 0.00367

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "61.46"
    },
    "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": 106,
          "rows_produced_per_join": 106,
          "filtered": "100.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "11.91",
            "eval_cost": "10.60",
            "prefix_cost": "22.51",
            "data_read_per_join": "81K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ],
          "attached_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`pfv`.`feature_id` in (656,658)) and (`softwarepirmam_hewadelivard_cscart_4`.`pfv`.`product_id` in (908,3090,2752,1143,2559,2822,2253,2751,2255,2927,2729,3140,1542,3026,853,1540,1544,2251,2252,2254,2869,2877,2788,2795,2936,2792,3021,3373,3011,2760,3060,2880,3014,3404,3366,3160,3023,3099,2800,2860,2775,2767,2562,3548,5151,2786,5126,5133,8703,7873,7871,7874,10455)) and (`softwarepirmam_hewadelivard_cscart_4`.`pfv`.`lang_code` = 'en'))"
        }
      },
      {
        "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": 5,
          "filtered": "5.00",
          "cost_info": {
            "read_cost": "26.50",
            "eval_cost": "0.53",
            "prefix_cost": "59.61",
            "data_read_per_join": "6K"
          },
          "used_columns": [
            "variant_id",
            "feature_id",
            "position"
          ],
          "attached_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`fv`.`feature_id` = `softwarepirmam_hewadelivard_cscart_4`.`pfv`.`feature_id`)"
        }
      },
      {
        "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": 5,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "1.33",
            "eval_cost": "0.53",
            "prefix_cost": "61.47",
            "data_read_per_join": "16K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}