How would I use two keys to activate?

This is a sort of difficult thing to do. I actually wrote a module that, among other things, handles this. Check it out here

Here's a demo:

local UserInputService = require(MODULESCRIPT) -- "Overwrites" default UIS
local Keys = UserInputService.Keys

local LeftAlt = Keys.LeftAlt
local Q = Keys.Q

local Parent = script.Parent

local Connection = (LeftAlt + Q):Connect(function()
	Parent.Enabled = not Parent.Enabled
end)

If you really want to do it without using a ModuleScript, there is a way. I recommend using the way above, because it is much cleaner, and I wrote it to be as efficient as the following way (as far as calling the function goes). If you write a game with a lot of different Keys that trigger things, it's easier to use the above syntax. If you want to do it the long way, here is how you might go about it:

local Players = game:GetService("Players")
local UserInputService = game:GetService("UserInputService")

local Q = Enum.KeyCode.Q
local LeftAlt = Enum.KeyCode.LeftAlt

local Player = Players.LocalPlayer
local Parent = script.Parent
local GuiEnabled

UserInputService.InputBegan:Connect(function(Input, GuiProcessed)
	if not GuiProcessed and Input.KeyCode == Q then
		local KeysBeingHeldDown = UserInputService:GetKeysPressed()

		for i = 1, #KeysBeingHeldDown do
			if KeysBeingHeldDown[i].KeyCode == LeftAlt then
				if GuiEnabled then
					GuiEnabled, Parent.Enabled = false
				else
					GuiEnabled, Parent.Enabled = true, true
				end
				
				break
			end
		end
	end
end)