SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '67ac2ad7074a58984838a3462d864845044a2ee54bf70f78688150dc8a8b0180' 
  AND token = 'lghKhl+II4sBAY2k1LZMWYXjvsr4Wqdwh6vI3JKR9+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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