SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '504589f0e6e335b3927ee2667a4a5aecbce46616a7532f324d55bf68ce0cc8ad' 
  AND token = '9W+CETIFuvZuNbsnn15Trh78st0QA5JD1wsAw4juyyE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}