SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a14a532afee20e13a7b404b09b9007645d2b8f3fb962d29a87dce01870fc265' 
  AND token = '4cxmPDELw923ULWxW8RZLYuI27a7IqkJNAuurQIfigE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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