Several warnings get thrown, while the migration tool is trying to upgrade Lock_ table.
WARN [main][UpgradeProcess:446] Attempting to upgrade table Lock_ by recreating the table due to: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'key varchar(255)' at line 1
You can see in the logs, that table Lock_ gets upgraded eventually, so this warning is pretty harmless:
WARN - Successfully recreated and upgraded table Lock_
- Upgrading to Liferay DXP 7.0, 7.1 or 7.2
To get rid of these warnings disable indexing before the upgrade as per this article: Disable Indexing