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 = 'vi' 
WHERE 
  pfv.feature_id IN (
    21924, 21597, 24202, 19924, 23237, 22338, 
    19922, 19643, 20454, 23490, 22336, 
    19795, 21265, 23755, 20984, 20981, 
    23924, 20983
  ) 
  AND pfv.product_id IN (
    1042, 1534, 41231, 5833, 31641, 400, 
    5835, 6562, 3885, 33716, 25733, 6068, 
    33717, 36781, 2563, 2566, 38146, 2564
  ) 
  AND pfv.lang_code = 'vi'

Query time 0.01352

JSON explain

{
  "query_block": {
    "select_id": 1,
    "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": "PRIMARY",
          "key_length": "6",
          "used_key_parts": ["feature_id", "product_id"],
          "rows": 354,
          "filtered": 0.056452893,
          "attached_condition": "pfv.feature_id in (21924,21597,24202,19924,23237,22338,19922,19643,20454,23490,22336,19795,21265,23755,20984,20981,23924,20983) and pfv.product_id in (1042,1534,41231,5833,31641,400,5835,6562,3885,33716,25733,6068,33717,36781,2563,2566,38146,2564) and pfv.lang_code = 'vi'",
          "using_index": true
        }
      },
      {
        "table": {
          "table_name": "fv",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "feature_id"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "ref": ["dev_db.pfv.variant_id"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "fv.feature_id = pfv.feature_id"
        }
      },
      {
        "table": {
          "table_name": "fvd",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["variant_id", "lang_code"],
          "ref": ["dev_db.pfv.variant_id", "const"],
          "rows": 1,
          "filtered": 100,
          "index_condition": "fvd.lang_code = 'vi'"
        }
      }
    ]
  }
}