SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '083ce3fdcb5a1dc128e1bfebb759623f3e2f54dcf5f27e8e58e71b37e8d79359' 
  AND token = 'nAYflQIsqTlptnaFGk+JT7avnnSgAhZYOQWBPHQVCjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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