Is there a way to test if a key is down in an if then statement?

Is there a way to test if a key is down in an if then statement? I tried to substitute the if then statement with a function, but the wait(.1) didn't work. I am trying to set off and explosion if the space bar has been help down after a jump. Any Ideas? this is a local script in StarterPlayerScripts.

local character = script.Parent
local humanoid = character:WaitForChild("Humanoid")
local player = game.Players.LocalPlayer
local mouse = player:GetMouse()
local debounce = 0

humanoid.Jumping:connect(function(key)
	wait(.1)
	mouse.KeyDown:connect(function(key)
    	if key:lower() == " " then
			if debounce == 0 then
				debounce = 1				
				if not character:FindFirstChildOfClass("ForceField") then
					local ForceField = Instance.new("ForceField", character)
					ForceField.Visible = false
				end
				wait(0.2)
				local Explosion = Instance.new("Explosion", character)
				Explosion.Position = character.HumanoidRootPart.Position
				Explosion.Visible = false
				debounce = 0
			end
    	end
	end)
end)

UserInputService:IsKeyDown returns a true/false depending if the key is being held down or not.

humanoid.Jumping:connect(function()
	    wait(.1)
	    mouse.KeyDown:connect(function(key)
	        if key = key:lower(" ")  then

do this at the start instead this will check if you press down spacebar