SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ad7cbee6636f3618bb9a4dd20132f07939a462fd012043e561c7f890cbc4fad' 
  AND token = 'SaGHAQQBkLbFjYosxIfjL36hhO3OK74GbtHvoHqmpJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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