static class Program
{
    static void Main()
    {
        ServiceBase[] ServicesToRun;
        ServicesToRun = new ServiceBase[]
        {
            new MyService()
        };
        ServiceBase.Run(ServicesToRun);
    }
}


public partial class MyService : ServiceBase
{
    private bool IsRunning;

    private static string ConnectionString
    {
        get
        {
            return ConfigurationManager.ConnectionStrings["MyConnection"].ConnectionString;
        }
    }

    public MyService()
    {
        InitializeComponent();
    }

    protected override void OnStart(string[] args)
    {
        this.IsRunning = true;
        this.Agendar();
    }

    protected override void OnStop()
    {
        this.IsRunning = false;
    }

    private void Agendar()
    {
        if (!this.IsRunning)
            return;
        var processo = Task.Run(Processar);
        processo.ContinueWith(task =>
        {
            Console.WriteLine(task.Exception);
        }, TaskContinuationOptions.OnlyOnFaulted);
    }

    private async Task Reagendar()
    {
        await Task.Delay(TimeSpan.FromMinutes(5));
        this.Agendar();
    }

    private async Task Processar()
    {
        try
        {
            using (var conexao = new SqlConnection(MyService.ConnectionString))
            {
                await conexao.OpenAsync();
                using (var comando = new SqlCommand(Properties.Resources.MyQueryName, conexao))
                {
                    var sqlDepedency = new SqlDependency(comando);
                    sqlDepedency.OnChange += (sender, e) =>
                    {
                        this.Agendar();
                    };

                    (await comando.ExecuteReaderAsync()).Close();
                }
            }
        }
        catch (Exception err)
        {
            Task.Run(Reagendar);
            Console.WriteLine(task.Exception);
            return;
        }

        this.DoSomeWork();
    }

    private async Task DoSomeWork()
    {
        using (var contexto = new MyDbContext())
        {
            // regras de negocio.
        }
    }
}

(await comando.ExecuteReaderAsync()).Close();