SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f1b6ca6e62970f4f83a5aae42829d4836fd05afd267b868053ac22a7334b9140' 
  AND token = 'J+7PVCFI/VdIbhkZwXg3+VK1csatm/d1tN7lsXEcMqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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