SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85f1dcf3a85ed1f1bed0847e3c57556e79ee0dde6359681611ad3f9932eef31d' 
  AND token = 'e51dYgKEYtwanNB6TM613R5AdqJxOkXL7qiqt26peN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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