SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8f6455904c8a6a2450693b3992f1326079ef99d468eb70b170ad12bddd08e86' 
  AND token = 'RIUZSkTGtx6KE2WPJJlawkDATik0RLntK+8TqLtV5ko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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