CREATE TABLE table_name_10 (lead_envoy VARCHAR(255), year VARCHAR(255), ryūkyūan_king VARCHAR(255), mission_type VARCHAR(255))
Who was the lead envoy of the congratulation mission in 1718 with the Ryūkyūan King shō kei?
    
SQL: SELECT lead_envoy FROM table_name_10 WHERE ryūkyūan_king = "shō kei" AND mission_type = "congratulation" AND year = 1718