Wireless MESH networks are important for providing communication in conditions where communication infrastructure is limited or absent. In such networks, encryption key management plays an important role in ensuring the security of data transmission. The work analyzes existing approaches to encryption key management in wireless networks and proposes a method for optimal key update. The method was tested on the LoRa EBYTE SX1262 chip with the ESP-WROOM-32. Algorithms for predicting update time were used.