I found this fare by accident. QR newly "improved" website does not show this fare, but it is bookable on QR website.
CTU-PRG
FARE CODE: RJHQP8ZE
TICKETS MUST BE ISSUED
ON/AFTER 10JUL 17 AND ON/BEFORE 19JUL 17.
VALID FOR TRAVEL COMMENCING
ON/AFTER 10JUL 17 AND ON/BEFORE 10DEC 17. ALL TRAVEL MUST BE COMPLETED BY MIDNIGHT ON 10DEC 17.