Without antivirus

yes, of course! Security, Antivirus, Firewall – S.A.F plugin have multiply different antivirus scan modes. First module for local antivirus scan it’s files monitoring. You don’t need to enable online anti virus scanner to get basic antivirus protection.
In such mode plugin start local scan according to time configurations and periods of scanning.
For more reliable protection from viruses on your server it’s better to enable local antivirus with online protection. With online antivirus plugin check files which was marked as dangerous also check online antivirus to make sure that everything will be fixed and protected.