SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e781ff89302d5971492fbd4a137fe675b285d50b02e29a051c7109573481766' 
  AND token = 'mDjbpgRfgZ4C+UwHzViYitsX3KV+giMekT7QxYaK++I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}