SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2f10d45b6cffc91ec51adf5cb2a871e1441b9fecde41c3a0b8baff79cf07e2f' 
  AND token = 'jKQ9AtxBElmY3oNXxeyCZPyQ5Wm0I3Bx7vK0c6hHd3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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