I have just flew out of HKT last night.
HKT is a very small airport. Security never takes more than 5-10 minutes for me and priority do exist. Most gates are also within <5 min walk proximity.
But depending on an airline, you can expect 15+ mins waiting in the queue at check-in, this is if you weren't able to OCI or have bags to check – and it is because some carriers only have about 3-4 desks open and there could be as many as 3 flights going out around the same hour. Even TG only has 1 desk for J and I think 2 for TG/WE Y pax.

I would worry more about getting stuck in traffic in the city and/or not making it to the airport before bag-drop cut off. If you don't require a visit to any of these, I'd say arrive around 45 minutes before departure.