SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f55f16fadb02932af7d1f4463abbadc90ffce341584dd564e83b423d4230d24' 
  AND token = 'eR7ZdPDcs787/KM1YFAd+7wCFnF0A6gS/AOfIT+BSVc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}