As long as the voltage is right, your device is safe. The 65W charger will be able to deliver 65W at the maximum whereas the 45W will only deliver 45 at the maximum. You can therefore use a charger that can go higher in power (and therefore in current) but you must respect the voltage of 19V. If you are at less than 19V, it may not turn on. If you are too high, it may be destroyed.
In summary: As long as you respect your 19V voltage, you can plug in a charger that has the capacity to deliver more.
