Internet of Things (IoT) based real-time health monitoring system gains the attention of the researchers as well as the business sectors. This service turns out to be a blessing to the patients as well as the health care professionals. However, without data security, the practical implementation of this vital healthcare service is not feasible. The sensitive nature of the patient’s healthcare data is very crucial and the compromise of such data may compromise one’s life. Therefore, in any IoT based healthcare system, data security is the vital issue. In this direction of IoT based healthcare system, this paper presents a survey of symmetric and asymmetric key management schemes. Considering the cryptographic key (symmetric or asymmetric), we have discussed the relevant studies within a time period of 6 years. A comparison of these schemes is presented with respect to the security features and simultaneously described the pros and cons of the respected schemes.