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 (
    68244, 68243, 68242, 68241, 68245, 69892, 
    69891, 69890, 69928, 69929, 69930, 
    70814, 70889, 70893, 70895, 70894, 
    70896, 70898, 70897, 70899, 71581, 
    71579, 71580, 73411, 73412, 73410, 
    73438, 73439, 73437, 73521, 73520, 
    74005, 74004, 74006, 74007, 81017, 
    81023, 81022, 81018, 81019, 81020, 
    81021, 81033, 81032, 81034, 84471, 
    84472, 85931, 85932, 86169, 86173, 
    86171, 86170, 86168, 86176, 86172, 
    86177, 86174, 86175
  )

Query time 0.00243

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": 59,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68244,68243,68242,68241,68245,69892,69891,69890,69928,69929,69930,70814,70889,70893,70895,70894,70896,70898,70897,70899,71581,71579,71580,73411,73412,73410,73438,73439,73437,73521,73520,74005,74004,74006,74007,81017,81023,81022,81018,81019,81020,81021,81033,81032,81034,84471,84472,85931,85932,86169,86173,86171,86170,86168,86176,86172,86177,86174,86175)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}