Contract Source Code:

/**
 *Submitted for verification at Etherscan.io on 2019-06-19
*/

pragma solidity ^0.5.0;

contract Lock {
    // address owner; slot #0
    // address unlockTime; slot #1
    constructor (address owner, uint256 unlockTime) public payable {
        assembly {
            sstore(0x00, owner)
            sstore(0x01, unlockTime)
        }
    }
    
    /**
     * @dev        Withdraw function once timestamp has passed unlock time
     */
    function () external payable { // payable so solidity doesn't add unnecessary logic
        assembly {
            switch gt(timestamp, sload(0x01))
            case 0 { revert(0, 0) }
            case 1 {
                switch call(gas, sload(0x00), balance(address), 0, 0, 0, 0)
                case 0 { revert(0, 0) }
            }
        }
    }
}