SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4724234fdb8147c5b7c63c1da9a6ec47d01505fbdbf3d3d42d31c420035484e5' 
  AND token = 'xXxgz0RzKkC9LuGZ0mAVDnFCIhc/dGBT2+vkUzXO1Ok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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