SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85da6c558f87b31f9280bf70e2675d83f29383940b80455ac5856ba2ded8a894' 
  AND token = 'SgdM0IYhrbygev7NNb4ESyfOoYRgO4zu786MDnZDprs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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