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 (
    68196, 68195, 68378, 68379, 68377, 68896, 
    68897, 81031, 69898, 69897, 69896, 
    70901, 70900, 70902, 71071, 71072, 
    71567, 71568, 71571, 71572, 72065, 
    72064, 72063, 72066, 73423, 73424, 
    73422, 73429, 73430, 73428, 73432, 
    73433, 73431, 73451, 73450, 73449, 
    74247, 74246, 74245, 74248, 74255, 
    74254, 74253, 74256, 75960, 75961, 
    75962, 75963, 75964, 75965, 75966, 
    75967, 78292, 78291, 78720, 78721, 
    78722, 78723, 78724, 78725, 78727, 
    78726, 80587, 80588, 80589, 81501, 
    81502
  )

Query time 0.01134

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": 67,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68196,68195,68378,68379,68377,68896,68897,81031,69898,69897,69896,70901,70900,70902,71071,71072,71567,71568,71571,71572,72065,72064,72063,72066,73423,73424,73422,73429,73430,73428,73432,73433,73431,73451,73450,73449,74247,74246,74245,74248,74255,74254,74253,74256,75960,75961,75962,75963,75964,75965,75966,75967,78292,78291,78720,78721,78722,78723,78724,78725,78727,78726,80587,80588,80589,81501,81502)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}