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 (
    68378, 68379, 68377, 69898, 69897, 69896, 
    69903, 69902, 69904, 70901, 70900, 
    70902, 71071, 71072, 73414, 73415, 
    73413, 73423, 73424, 73422, 73429, 
    73430, 73428, 73432, 73433, 73431, 
    73451, 73450, 73449, 73489, 73488, 
    74247, 74246, 74245, 74248, 74255, 
    74254, 74253, 74256, 75637, 75635, 
    75636, 80587, 80588, 80589, 86179, 
    86180, 86178, 86187, 86186, 86185, 
    86184, 86183, 86182, 86181
  )

Query time 0.00940

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": 55,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68378,68379,68377,69898,69897,69896,69903,69902,69904,70901,70900,70902,71071,71072,73414,73415,73413,73423,73424,73422,73429,73430,73428,73432,73433,73431,73451,73450,73449,73489,73488,74247,74246,74245,74248,74255,74254,74253,74256,75637,75635,75636,80587,80588,80589,86179,86180,86178,86187,86186,86185,86184,86183,86182,86181)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}