Despite being industry standard, load balancing via virtual machine (VM) migration methods in modern cloud data centers still exhibit two major performance issues: resulting system load balancing degree and total time till balanced state. Over the years research has been conducted to improve these metrics. Yet due to the fact that these issues influence each other, it has been a challenge to achieve substantial advancement in both metrics simultaneously. In this paper we study the problem of VM migration with load balancing and migration time constraints. We formulate this problem as a variation of multi-commodity minimum cost flow problem and show how both resulting degree of imbalance and a total migration time can be optimized together. We also propose a heuristic method based on Ant Colony Optimization family of algorithms. Through simulation results we show that our heuristic gives good performance results compared to optimal solutions to minimum cost flow problem. Furthermore, our method achieves on average twice faster migration time compared to existing methods, proposed in related works.