Online Social networks have provided the foundation for some new applications in recent years, e.g., for the recommendation of service providers or services. In these applications, trust is one of the most important indications for consumers' decision making that requires the evaluation of the trustworthiness of a service provider along the social trust paths from a service consumer to the service provider. However, there are usually many social trust paths. Also, some social information, e.g., social relationships and recommendation roles of participants, has significant influence on trust evaluation and should be considered. In this paper, we first present a novel complex social network structure incorporating trust and important social information. We also present a new concept, Quality of Trust (QoT), and model the optimal social trust path selection with multiple end-to-end QoT constraints as an NP-Complete Multi-Constrained Optimal Path (MCOP) selection problem. Towards solving this challenging problem, we propose a novel Multiple Foreseen Path Based Heuristic algorithm MFPB-HOSTP. The results of our experiments conducted on a real dataset of online social networks illustrate that MFPB-HOSTP can efficiently identify the social trust paths with better quality than our previously proposed H_OSTP algorithm that outperforms prior algorithms for the MCOP selection problem.