SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cff2cdd65b4a9a38d0badba98d53b3afcbbca21931a18cef103468b3bcfe9c8c' 
  AND token = 'LN+8MxnCi+0QiNWn31kkgVAWN8mhtaKzs2lfelxxH1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}