SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '31c585da9453d4603c167527fc12c96d659cb43faf2ab80ed4afbe829988fa9f' 
  AND token = '7IU+ptxKk4V+Km+Kx+S6x7WfCKNAXBs8HwOJOT2H4Kw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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