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 (
    68602, 68603, 70249, 70248, 70247, 70246, 
    70245, 70244, 70243, 70242, 70241, 
    71341, 71339, 71338, 71337, 71336, 
    71335, 71334, 71333, 71332, 71331, 
    71342, 74799, 74800, 74803, 74804, 
    74805, 74806, 75622, 75623, 75624, 
    75625, 75626, 76705, 76704, 76703, 
    76706, 81689, 81690, 81691, 84725, 
    84724, 82134, 82133, 82135, 82657, 
    82658, 82660, 82661, 86590, 86591, 
    86592, 86593, 86594, 86595, 87021, 
    87022, 87023, 87190, 87191, 87192, 
    84152, 87604, 84154, 87603, 87602, 
    87601, 84156, 84153, 87711, 87712, 
    87713
  )

Query time 0.00703

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": 72,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68602,68603,70249,70248,70247,70246,70245,70244,70243,70242,70241,71341,71339,71338,71337,71336,71335,71334,71333,71332,71331,71342,74799,74800,74803,74804,74805,74806,75622,75623,75624,75625,75626,76705,76704,76703,76706,81689,81690,81691,84725,84724,82134,82133,82135,82657,82658,82660,82661,86590,86591,86592,86593,86594,86595,87021,87022,87023,87190,87191,87192,84152,87604,84154,87603,87602,87601,84156,84153,87711,87712,87713)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}