How to check if KES is installed, its state (running or not) and bases version via registry:

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\KasperskyLab\Components\34\1103\1.0.0.0\Statistics\AVState

More information about these registry keys is available in Online Help: https://support.kaspersky.com/ksc14/3644.

Obtaining information from the registry is for familiarization purposes only. KESCLI commands method supported by developers:

Managing the application from the command line  >  KESCLI commands  >  GetRealTimeProtectionState. File Threat Protection status
https://support.kaspersky.com/help/KESWin/12.2/en-US/213719.htm

Managing the application from the command line  >  KESCLI commands  >  GetDefinitionState. Determining the update completion time
https://support.kaspersky.com/help/KESWin/12.2/en-US/213724.htm

Information in following registry is created by network agent (NA). Information will be deleted before OS shutdown and will be created after OS boot.

There is a delay (120s) for NA service start.  So if you need to get the state of KES immediately after OS boot, use KESCLI.