SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7fa535403894a36f9dbfb268aaf77a04349842967b90889345c6754d396c682' 
  AND token = '1HMQuRSSlwRTyrbBwfSN5Yem/BygPVMlU3i3tg9aPYk=' 
  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"
    }
  }
}