SELECT 
  pfv.variant_id, 
  pfv.position, 
  pfvd.variant 
FROM 
  cscart_product_feature_variants AS pfv 
  INNER JOIN cscart_product_feature_variant_descriptions AS pfvd ON pfv.variant_id = pfvd.variant_id 
  AND pfvd.lang_code = 'vi' 
WHERE 
  pfv.variant_id IN (
    81055, 81056, 81057, 81058, 81059, 81153, 
    81154, 81155, 81156, 81157, 81162, 
    81163, 82001, 82007, 82008, 82002, 
    82003, 82004, 82005, 82006, 82011, 
    82012, 82013, 82017, 82018, 82019
  )

Query time 0.00152

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "rows": 26,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (81055,81056,81057,81058,81059,81153,81154,81155,81156,81157,81162,81163,82001,82007,82008,82002,82003,82004,82005,82006,82011,82012,82013,82017,82018,82019)"
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "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": "pfvd.lang_code = 'vi'"
        }
      }
    ]
  }
}