using (ApplicationDbContext UsersContext = new ApplicationDbContext())
            {
                var user = UsersContext.Users.Where(x => x.UserName == key).First();
                user.LastActivityDate = DateTime.Now;
                UsersContext.SaveChangesAsync();
            }

using (ApplicationDbContext UsersContext = new ApplicationDbContext())
            {
                var user = UsersContext.Users.Where(x => x.UserName == key).First();
                user.LastActivityDate = DateTime.Now;
                UsersContext.SaveChanges();
            }

	exec sp_executesql N'UPDATE [dbo].[AspNetUsers]
SET [LastActivityDate] = @0
WHERE ([Id] = @1)
',N'@0 datetime2(7),@1 int',@0='2014-12-02 10:40:27.1523756',@1=1


exec sp_executesql N'UPDATE [dbo].[AspNetUsers]
SET [LastActivityDate] = @0
WHERE ([Id] = @1)
',N'@0 datetime2(7),@1 int',@0='2014-12-02 10:45:13.0687290',@1=1