How to set ng-disable using two variables

Assuming I have two flag as follows:

var myApp = angular.module('myApp', []);
myApp.controller('booleanController', function($scope, $interval){
$scope.isDisabled = false;
$interval(function(){
    $scope.isDisabled = !$scope.isDisabled;
  }, 1000)
})

And HTML as:

<div ng-app='myApp'>
<div ng-controller="booleanController">
    Disable Option<input type="checkbox" ng-model="disableIt">
    </br>
    Select Two <input type="checkbox" ng-model="checked">
    </br>
    <select ng-disabled="{{disableIt && isDisabled}}">  <=========
        <option value="1">One</option>
        <option value="2" ng-selected="checked">Two</option>
    </select>
</div>
</div>

How do I evaluate ng-disabled with the two expression disableIt and isDisabled?