#!/bin/bash
s=' Active: active (running) since Sat 2022-03-12 20:02:20 PKT; 1h 31min ago'
sed -nE 's/^ *Active: +(.* since ).*([0-9]{2}:[0-9]{2}:[0-9]{2}[^;]*).*/\1\2/p' <<< "$s"
IyEvYmluL2Jhc2gKcz0nICAgQWN0aXZlOiBhY3RpdmUgKHJ1bm5pbmcpIHNpbmNlIFNhdCAyMDIyLTAzLTEyIDIwOjAyOjIwIFBLVDsgMWggMzFtaW4gYWdvJwpzZWQgLW5FICdzL14gKkFjdGl2ZTogKyguKiBzaW5jZSApLiooWzAtOV17Mn06WzAtOV17Mn06WzAtOV17Mn1bXjtdKikuKi9cMVwyL3AnIDw8PCAiJHMi