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 (
    68320, 68321, 68322, 68323, 68341, 68340, 
    68339, 68338, 68342, 68839, 68838, 
    68837, 68836, 68840, 68896, 68897, 
    81031, 69618, 69617, 69622, 69621, 
    71557, 71556, 75522, 75521, 76738, 
    76737, 76739, 78285, 78292, 78291, 
    80587, 80588, 80589, 81033, 81032, 
    81034, 81505, 81506, 81507, 81508, 
    82207, 82217, 82218, 82219, 82220, 
    82222, 82223, 82224, 82208, 82209, 
    82210, 82211, 82212, 82213, 82214, 
    82216, 74389, 82449, 82450, 74391, 
    74392, 74393, 74394, 74395, 74396, 
    74397, 74399, 84334, 84333, 84332, 
    84331, 84330, 84329
  )

Query time 0.02751

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": 74,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68320,68321,68322,68323,68341,68340,68339,68338,68342,68839,68838,68837,68836,68840,68896,68897,81031,69618,69617,69622,69621,71557,71556,75522,75521,76738,76737,76739,78285,78292,78291,80587,80588,80589,81033,81032,81034,81505,81506,81507,81508,82207,82217,82218,82219,82220,82222,82223,82224,82208,82209,82210,82211,82212,82213,82214,82216,74389,82449,82450,74391,74392,74393,74394,74395,74396,74397,74399,84334,84333,84332,84331,84330,84329)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}