SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f91fcc409f1a510a5ef61254e325a80b9a505f4f83c95ba30fa8cac015c31235' 
  AND token = 'TwdRQxhiZyKq4bGFWveZPRJZo/2qE6pB3EuLTCs/FPk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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