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 (
    20436, 20437, 23738, 23740, 20279, 20440, 
    22571, 23494, 20429, 23741, 24437, 
    22568, 24096, 22367, 23730, 23512, 
    22578, 23733, 24094, 24095, 24201, 
    22236, 24717, 20435, 23728, 20430, 
    23496
  ) 
  AND pfv.product_id IN (
    3978, 3977, 49256, 36307, 4381, 3974, 
    2252, 33709, 3988, 36717, 43650, 2249, 
    40535, 353, 36295, 33721, 2260, 36300, 
    40532, 40527, 41230, 25159, 49309, 
    3979, 36293, 18710, 33835
  ) 
  AND pfv.lang_code = 'vi'

Query time 0.05461

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": 506,
            "selectivity_pct": 0.319840206
          },
          "rows": 164,
          "filtered": 0.319840193,
          "index_condition": "pfv.product_id in (3978,3977,49256,36307,4381,3974,2252,33709,3988,36717,43650,2249,40535,353,36295,33721,2260,36300,40532,40527,41230,25159,49309,3979,36293,18710,33835)",
          "attached_condition": "pfv.feature_id in (20436,20437,23738,23740,20279,20440,22571,23494,20429,23741,24437,22568,24096,22367,23730,23512,22578,23733,24094,24095,24201,22236,24717,20435,23728,20430,23496) 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'"
        }
      }
    ]
  }
}