So let me explain why antivirus are useless.
Any installed app from the google play store and from third party will be sanboxed by android, That means that they have limitation on what they can do such as accesing other app data and private directories,accesing low level of the system,ect... which explains why they have to ask for permission to do certain things first. Now the only issue with that is the fact that antivirus are no execption, once an malicious app is installed, its too late for the antivirus app to react. Because it cant look in there, it wont be able to check those parts of the system and it will not realises there is malware because the sandbox cant let him do that., even their find my phone is not useful because that is already built in Android, heck there is even a built in malware scanner to android! that scans third party apps you install for malicious behaviour even Google plays one are scanned and it will be automatically uninstall them on all devices that has the app in question(but only if its in google plays) so basically you might want to use it only if you actually downloading shady application of shady website.