SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f12158850dd96a9f4a961effb2ad87e1737ce42d6fad68235c5e0e8e982c15a7' 
  AND token = '3cOzSPrj2vC4LWoTV7iFvGphAzYQjQGaBVNKCfuZFGM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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