Lock itself is temporary, it will last for 120 minutes and account will be unlocked again.
But the thing is, if your ESXi host still remains exposed to insecure public network then chances of your root account getting locked are very high. Just within next few seconds you might find account got locked again.
Please refer following URLs, see if those are helpful.
vSphere 6.0 Documentation Center
VMware Front Experience: Watch out: ESXi 6.0 introduces root account lockout!