If your wallet is encrypted/locked and you don't know how to/don't want to decrypt it, follow these steps.  
1.Open Bitcore
2.Click file
3.Sign message.  

follow screenshot below.


https://i.imgsafe.org/5c/5cf89c6380.jpeg

When you click 'sign message' it will ask for your passphrase.

https://i.imgsafe.org/5c/5cf8b2d7ae.jpeg