TLS Client, connection pooling in lua

Does anyone aware of a lua library that allows tls client pooling? We have a kong custom plugin which checks the validity of a session id against a rest endpoint protected using x.509 client cert id, if session id is invalid the plugin blocks access to the upstream.
The rest endpoint’s latency is below 1ms, since the plugin makes a tls call, the tls handshake itself take about 40-60 ms on every request which is not acceptable to our customers,
I tried use luasocket tcp.setoption (‘keepalive’,true) to the connection open for the subsequent requests that didn’t seem to keep the connection open.

Any suggestion is appreciated.

Thank you.