A Race Against Time is a quest found in Wrath of the Lich King Classic in the Borean Tundra, which is one of the zones you might arrive in when you head to Northrend for the first time. You'll get this quest from Librarian Donathan at the Amber Ledge, a hub located on the coast to the north of Warsong Hold.
The objective for this quest might seem pretty straightforward, but it's not easy to figure out where you're supposed to get the item needed to complete it. So when you're ready, here's how to find Salrand's Broken Key and complete Wrath Classic's A Race Against Time quest.
WotLK Classic A Race Against Time: Where to find the key
After accepting the quest, you should find the Beryl Shield Detonator item in your bags. You're going to need this to break Salrand's shield and defeat her to get the key.
You'll find several circular blue platforms just to the southwest of the Amber Ledge and you need to head to the largest of these. It's pretty easy to spot as it's the one with the glowing blue barrier around it. There are a number of enemies patrolling inside of it and you should see Salrand herself, floating in the centre. Use the Beryl Shield Detonator by throwing it anywhere inside the shield to deactivate it, then you're free to kill the enemies inside.
Once Salrand has been defeated, a small lockbox will spawn in the centre of the platform and you can loot Salrand's Broken Key from there.
If the area is particularly busy with other players and someone else tags Salrand, don't worry. You should still be able to loot the key from the box and complete the quest.