Here, we have to sign unlock message with ECDSA without provided private key, but with possibility to sign some restricted messages. In ECDSA signing should be performed with cryptographically secure random integer k less than n, which is integer order of G. In provided algorithm, n variable is assigned to number of second in current time, which is between 0 and 59, so used k will also be in this range. With the knowledge of value of k, we can calculate private key and sign every message we want. As there aren't many possible values of k, we can brute force it by assuming it is equal to 1 and check if further calculations will give flag.
crypto{ECDSA_700_345y_70_5cr3wup}