SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6b6d0522c9c28a04653e62b3538c59efa46cc3bc29406585357bd036cef0f14' 
  AND token = '43ZuTiQF7CgCqGFCWiYnSMSdJ1btv43FIKRG6+YuBWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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