The huge amount of data produced by billions of distributed Internet of Things (IoT) devices creates unprecedented opportunities for several fields and industries. These data can drive informed decision-making, enhance operational efficiency, and improve the quality of life for individuals and communities. IoT data marketplaces have evolved as a solution to allow trading data assets, where data consumers can acquire IoT data streams to improve data analytics and offer innovative services, while data providers can monetize their IoT data. The realization of trustworthy marketplace, however, faces significant impediments due to the lack of mutual trust between data providers and consumers with the absence of a central marketplace operator trusted by all entities. In this paper, we focus on developing a trustworthy and decentralized solution for real-time IoT data marketplaces. First, we propose Multi-authority Attribute-Based Encryption with Revocation and Accountability (MABERA), a novel trustworthy Multi-authority Attribute-Based Encryption (MA-ABE) that supports attribute-level revocation and accountability. Then, we propose a trustworthy and decentralized solution for real-time IoT data marketplaces that integrates MABERA with several cryptographic primitives to ensure data confidentiality, fair exchange, fine-grained access control, and accountability. We demonstrate that our solutions provide the desired security properties, and the simulation results show that our solutions are feasible and efficient.