Android Back Button Event cause Applicantion crash

hi, I’m trying to develop and application for Android Platform, and even with the following code, if I press the virtual back button on my nexus5 the app crash and the screen keep blocked for a while. How can I fix that?
using UnityEngine;
using System.Collections;

public class intercep_key : MonoBehaviour {

	// Use this for initialization
	void Start () {
	
	}
	
	// Update is called once per frame
	void Update () {
        
            if (Input.GetKey(KeyCode.Escape)) 
			{ 
				Application.Quit(); 
			}
	}
	
}

Make the Input.GetKey an Input.GetKeyDown. Maybe it’s firing too often your way.