reset Input.GetButton ("Fire1") when button not pressed

Hi!

What I want to archieve:

I would like to have the button pressed for a period of time to open a chest box for instance.
Like - hold down the button for 3 second → open chest box. When button released is released before 3, reset the timer and do nothing. When pressed and hold, count again…

I am using a simple script to get a button event while the mouse button is pressed like this:

using UnityEngine;
using System.Collections;

public class charge_hit : MonoBehaviour {

	public float chargeMove;
	public float chargeMoveTimer = 1;

	 
	// Update is called once per frame
	void Update () {

		if (Input.GetButton("Fire1") ) 
		{

			chargeMoveTimer+=Time.deltaTime;

		}

		if ((Input.GetButton("Fire1")) && (chargeMoveTimer>5))

		{

			print("Open Something!");

		}

		if ((Input.GetButton("Fire1")) && (chargeMoveTimer<5))

		{

			print("Not Open!");

		}


	
	}
}

How coud I archieve to get ChargeMoveTimer reset after the button is not pressed any longer,
so the counter restarts the next time I press the button.

Thanks!

if (Input.GetButton(“Fire1”)) {

         chargeMoveTimer+=Time.deltaTime;
         if(chargeMoveTimer>=5){
               print("Open Something!");
               chargeMoveTimer = 0;
         }else{
               print("Not Open!");
         }       

     }else{
           chargeMoveTimer = 0;
     }