SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'eb0b55da8c92118a1f166406065d1a0e95773ecb2538320dced0fc655312ca82' 
  AND token = '/ZplQFZiNIIdCjwhy7u55qV+ZOPB4S40nDHXKk0KvDY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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