What does "Latest Restore Time" says in AWS RDS(Mysql) instances page
Given the RDS Console tooltip, the Latest Restore Time defines The latest time to which a database can be restored with point-in-time restore. and not the last time the database was restored.

The database can be restored from Amazon RDS Automated Backup tool that can be configured in the Amazon RDS Modify DB Instance page. The default window backup is 7 days, every 30 minutes.