Validation API Rest with Header Auth

I created an endpoint and i’m sending a post from an external url to my endpoint myurl.com/wp-json/my_plugin/v3/my_function with header authentication (Username = CK and Password = CS), when I receive the parameters in my callback, how to validate the CK and CS, creating a function that queries the database? or is there any other way to validate this information?

    add_action( 'rest_api_init', function () {
         register_rest_route( 'my_plugin/v3/', 'my_function', array(
              'methods'  => 'POST',
              'callback' => 'my_callback'
         ));
    });

    function my_callback(){
         $usr = $_SERVER[ 'PHP_AUTH_USER' ];
         $pwd = $_SERVER[ 'PHP_AUTH_PW' ];
         //validate logic:
         //hook, action or database verification??
         // execute my custom action...
    }