How to validate access token in Ionic 3?

I'm working on Ionic-Laravel app, and using Laravel Passport for authentication. These are my questions about authentication:

Q1: Is there any way I can validate the access token in ionic app (like in JWT .isTokenExpired())?

Q2: When User-X logs in, the access token is either stored in SQLite or LocalStorage. If User-Y steals this access tokens, can he log in as User-X? Or my understanding about access token is wrong?

Q3: If I'm right about Q2, what is the better approach to store the access token in the ionic app?

via Chebli Mohamed