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, 69908, 
    69907, 69909, 69914, 69913, 69915, 
    69920, 69919, 69939, 70814, 70889, 
    70893, 70895, 70894, 70896, 70898, 
    70897, 70899, 72911, 72912, 72966, 
    72967, 73438, 73439, 73437, 73521, 
    73520, 81033, 81032, 81034, 81215, 
    81223, 81222, 81221, 81220, 81219, 
    81218, 81217, 81216, 81679, 81683, 
    81684, 83214, 83215, 87282, 87278, 
    87281, 87280, 87279, 87603, 87608, 
    87606, 87607, 87609, 87605, 87604, 
    87610, 87611, 87612, 87613
  )

Query time 0.00474

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": 65,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68244,68243,68242,68241,68245,69908,69907,69909,69914,69913,69915,69920,69919,69939,70814,70889,70893,70895,70894,70896,70898,70897,70899,72911,72912,72966,72967,73438,73439,73437,73521,73520,81033,81032,81034,81215,81223,81222,81221,81220,81219,81218,81217,81216,81679,81683,81684,83214,83215,87282,87278,87281,87280,87279,87603,87608,87606,87607,87609,87605,87604,87610,87611,87612,87613)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}