Smart contract hacking

Say in the target smart contract , it has :
bytes32 slot = keccak256(abi.encodePacked(block.timestamp, blockhash(block.number - 69)));

by etherscan deployment , i know the timestamp is Mar-25-2023 10:57:12 AM +UTC
i want to convert "Mar-25-2023 10:57:12 AM +UTC" into something that can take as the parameters of the keccak hash function , so that i can compute the slot value .

any ideas on this ?