SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4b5b7046ac34182ab8831bb3a27f00b93a40a0cc04c2457f80e415cae71315fd' 
  AND token = 'fsuDyzfSok89FEx3IP/CroU4CI22H60NZ4FPuaODI0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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