Is there a tool to check mysql/mariadb database is all OK?
Verifying that a MariaDB or MySQL instance is "OK" is a complicated task, not least because there are different levels of "OK", and one man's "OK" is another man's "not OK". There are various tools you can use, though. To name a few in no particular order:


Percona Toolkit's pt-variable-advisor
SHOW ENGINE ... e.g. SHOW ENGINE INNODB STATUS\G, 
Activate and check the slow query log 
PMM - Percona Monitoring &amp; Management
MONyog
mysql-tuner, see e.g. article here.