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 (
    21926, 23703, 20277, 21954, 21955, 20063, 
    23709, 22577, 19730, 22566, 20050, 
    23735, 23926, 22574, 23539, 21951, 
    20276, 23734
  ) 
  AND pfv.product_id IN (
    1040, 36469, 4383, 979, 978, 5381, 36466, 
    2259, 15235, 2248, 5420, 36303, 38151, 
    2256, 35193, 982, 4384, 36302
  ) 
  AND pfv.lang_code = 'vi'

Query time 0.01100

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": 350,
          "filtered": 0.039731704,
          "attached_condition": "pfv.feature_id in (21926,23703,20277,21954,21955,20063,23709,22577,19730,22566,20050,23735,23926,22574,23539,21951,20276,23734) and pfv.product_id in (1040,36469,4383,979,978,5381,36466,2259,15235,2248,5420,36303,38151,2256,35193,982,4384,36302) 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'"
        }
      }
    ]
  }
}