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 (
    21326, 24566, 24567, 20474, 24444, 21157, 
    23527, 23531, 23533, 23530, 23529, 
    24551, 24569, 23622, 23623, 21665, 
    21158, 22512, 24836, 20545
  ) 
  AND pfv.product_id IN (
    1977, 44944, 3864, 43825, 2291, 35167, 
    35174, 35176, 35172, 35171, 44947, 
    35731, 23261, 2288, 118, 47656, 49192
  ) 
  AND pfv.lang_code = 'vi'

Query time 0.01079

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": "product_id",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "rowid_filter": {
            "range": {
              "key": "fl",
              "used_key_parts": ["feature_id", "lang_code"]
            },
            "rows": 369,
            "selectivity_pct": 0.233243154
          },
          "rows": 92,
          "filtered": 1.993507862,
          "index_condition": "pfv.product_id in (1977,44944,3864,43825,2291,35167,35174,35176,35172,35171,44947,35731,23261,2288,118,47656,49192)",
          "attached_condition": "pfv.feature_id in (21326,24566,24567,20474,24444,21157,23527,23531,23533,23530,23529,24551,24569,23622,23623,21665,21158,22512,24836,20545) and pfv.lang_code = 'vi'"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}