Sure, you can check whether the port is in use, however that doesn't mean the server is up and responding. For non-distributed LASR server the best way to check whether the server is up and responding is to write a wrapper script that starts Base SAS and connects to the LASR server using the SASIOLA engine.
LIBNAME LASR SASIOLA TAG=<YOUR_TAG> PORT=<YOUR_PORT> SIGNER="https://<YOUR_MIDDLE_TIER_URL>/SASLASRAuthorization" HOST="<YOUR_LASR_HOST>" ;
LIBNAME LASR clear;