A control lock may only stop settings being changed. It should not be assumed to lock the physical door or make the appliance safe for unsupervised play.
What the observation tells you
The meaning of the padlock symbol depends on the model. An accessory strap sold separately also has its own limitations and can interfere with closure if fitted incorrectly. Never rely on an unfamiliar symbol as a child-safety system.
A useful next step
Read the precise control description and supervise children appropriately. Keep the door and vents unobstructed. If an aftermarket fitting is present, mention it when describing a closure problem so its effect can be considered.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.