Do you recommend using cleanmymac3?
I would strongly recommend not using third-party utilities like CleanMyMac or MacKeeper on your computer. Although they do in some cases allow you to trigger specific maintenance type actions like clearing inactive processes from your system's active memory most versions of macOS take care of that type of maintenance all on their own.
Regarding anti-malware applications specifically, it's important to understand that even Macs are impacted by malicious software. Although Apple does go out of their way to make sure that security vulnerabilities are addressed as quickly as possible sometimes attackers are able to get an exploit into the wild fast enough to infect un-patched devices.
In some cases a third-party anti-malware application would be able to catch an infection like this, but in addition to this type of protection many of these pieces of software take over or modify other parts of your system that could actually make you MORE vulnerable to some types of attacks.
My general policy is to leave security and optimization to Apple and make sure that my devices are fully up to date. Safe browsing habits like not navigating to websites you do not recognize and using an ad-blocker are the most impactful steps that you can take without making compromises elsewhere.