A key employee or key independent contractor may enter into a written agreement or covenant that protects the employer’s legitimate business interests and prohibits the key employee or key independent contractor from engaging in employment or a line of business that is in direct competition with the employer’s business after termination of employment, and the same shall be enforceable, if the agreement or covenant is reasonable as to its duration, geographical area, type of employment or line of business, and does not impose a greater restraint than is reasonably necessary to protect the employer’s legitimate business interests.