The application areas of Wireless Sensor Networks (WSNs) are expanding with time. Many of these applications demand a lower end-to-end delay, high throughput, and energy-efficient operations. The performance of these applications mostly relies on the performance of the MAC protocol. This paper presents a Dual-Channel Dual-Slot MAC (DCDS-MAC) protocol for WSNs, which significantly reduces the end-to-end delay and improves the throughput while ensuring energy-efficient operations. In the proposed protocol, the delay problem of existing Lightweight MAC (LMAC) and Multi-Channel LMAC (MC-LMAC) protocol has significantly improved by using suitable destination selection technique by data packet sending node and allowing a node to transmit its packet using a timeslot pair of a channel over two different channels. The timeslot pair is kept half of the frame time separated which is decided by an algorithm. Moreover, the schedule-based operations ensure an energy-efficient operation and use of two-channel results high throughput. Finally, extensive simulations are carried out in OMNeT++ to compare the performance of proposed DCDS-MAC protocol with the existing LMAC and MC-LMAC protocol, in terms of received packets, delay, energy consumption and network lifetime. Simulation results ensure that the proposed protocol performs a significant improvement in delay and throughput over existing protocols without consuming much energy.