SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1e9e6e45717746f36f681b8e04d5d8c9af8c4f582455f2cb3516d3c6c1f97af' 
  AND token = 'DBBfJKTezWQyiBgpdTiaIjcKhT0MljYYqkIhNUj+vk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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