Set two different lock setting on different triggers

You could use Android's Smart Lock feature for this, see e.g.:

• Use Smart Lock in Android 5.0 and Never Unlock Your Phone at Home Again


• How to use Trusted Devices in Android

If you have e.g. any Bluetooth device, you can tell your Android device it's "safe" as long as it can see it (so: no lock), but "not safe" otherwise (device gets locked). To have your device locked, you'd simply have to shutdown or disconnect the BT device (or have it out-of-reach; for Bluetooth-devices usually being away 10m is enough – even less with walls in between).

Smart Lock works natively with Android 5+ – and for earlier versions, there are fitting apps (e.g. Zwype Lock Screen, SkipLock, or using one of the more generic automation solutions to build your own: I e.g. use tasker with the Secure Settings plugin for this).