This is a tough call there are many snakes that can kill you within an hour if you can’t get medical care.
I guess the King Cobra, if it got a good bite on you – would be the worst. I have a friend who lost his little brother (adult brother) to a King bite on the chest that killed him in just 10 minutes.
If you are allergic to the venom of the snake that bites you, death could come even sooner. Some snake experts recommend carrying around a Ventolin inhaler that people use for asthma treatment. If bitten by a venomous snake in Thailand you may start losing your breath. That’s when to take a spray.
I always have one with me – I am slightly asthmatic so, in this case it’s a good thing.