SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c081cf50983da42476deaae60746608e11e2183b381ec9047b958d0b342d495b' 
  AND token = 'WicD0QibMTG0GZ9+ipejqbu4o+yf0u/dMjgnjVvobY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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