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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc371608002e8c21d56fcb24e19d386dd803ed4a8f6e191bcdeee7861f0de214' 
  AND token = 'PVDVpKJ3Jsb/e9LEmkyXPcdsrMWyYkkxTFAeMh8qgjE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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