Yes, they can access your phone if they want to, but accessing the data is another story. You’d have to be a very high profile target for them to try attacking your phone, and if it’s off, they’d have to break the encryption. AFAIK, the “Israeli exploits” aren’t magic, and it’s not something they’d even try in a typical airport check.

If you’re really worried about it, mall your phone to your destination, those have a lot less security.