Not only can SKLM be deployed in an HA configuration, but it is recommended. With SKLM v3.0, its Multi-Master capabilities allow up to 21 master SKLM servers to be deployed and globally distributed.
All SKLM servers can synchronize their keys is real-time so that no data center will be isolated without its keys. SKLM can be deployed on-prem or in cloud configurations with synchronization across those environments, so your keys are always available and under your control.