minor optimization for paranet_synced_asset table, ual index

[botnumberseven]

During paranet sync process node execute a lot of queries like this (see below).

I've added index below and it helped to reduce time for these SELECT to complete, as well as resource consumption a bit.
ALTER TABLE paranet_synced_asset ADD INDEX idx_ual (ual);

SELECT
id
, blockchain_id AS blockchainId
, ual
, paranet_ual AS paranetUal
, public_assertion_id AS publicAssertionId
, private_assertion_id AS privateAssertionId
, sender
, transaction_hash AS transactionHash
, data_source AS dataSource
, created_at AS createdAt
, updated_at AS updatedAt
FROM paranet_synced_asset AS paranet_synced_asset
WHERE paranet_synced_asset.ual = 'did:dkg:base:84532/0xb8b904c73d2fb4d8c173298a51c27fab70222c32/6239745'
LIMIT 1