SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '398d26249f691c0153a338378caa35314454e342b199189282c3b566f4260a53' 
  AND token = 'aE+sISR6loeJNcCpNPMZZhkJd1rqmZgneWCehsy8y1Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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