A Wizard casts Arcane Lock upon a door. The spell description explicitly says that the spell will make it "more difficult to break":
While affected by this spell, the object is more difficult to break or force open; the DC to break it or pick any locks on it increases by 10.
How difficult would it be for the bad guys to break the door? "DC increases by 10" mechanic is irrelevant, since DMG operates AC and hit points for breaking objects (see DMG page 246, "Objects"):
For the purpose of these rules, an object is a discrete, inanimate item like a window, door ...
When time is a factor, you can assign an Armor Class and hit points to a destructible object.
Here is a relevant question - Does Arcane Lock Make An Object More Resistant to Damage? - but its answer only describes a trivial fact that RAW the Arcane Lock spell doesn't change the object's HP or AC.