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 (
    21340, 20885, 20891, 21347, 21341, 20890, 
    21343, 21339, 21346, 21338, 24568, 
    24569, 24552, 24551, 24566, 24567, 
    24867, 24481
  ) 
  AND pfv.product_id IN (
    22172, 2873, 2854, 22268, 1942, 2857, 
    22214, 1945, 22263, 1946, 44946, 44943, 
    44944, 44947, 47974, 44945, 44281
  ) 
  AND pfv.lang_code = 'vi'

Query time 0.01557

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": 339,
          "filtered": 0.539834857,
          "attached_condition": "pfv.feature_id in (21340,20885,20891,21347,21341,20890,21343,21339,21346,21338,24568,24569,24552,24551,24566,24567,24867,24481) and pfv.product_id in (22172,2873,2854,22268,1942,2857,22214,1945,22263,1946,44946,44943,44944,44947,47974,44945,44281) 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'"
        }
      }
    ]
  }
}