SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '786d9424ae4715417acaa0fccc67f225bc13da3599e36e03dec80be70cac44cc' 
  AND token = 'ihhYL45WfWLQOlFmmYTr1iFhxZHY70pTmgbwMEUyIk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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