SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8543930950794152156ff28514adf50143a7ba0fa274401ffb726e4bb914f583' 
  AND token = 'jdKFs922EcZ/hzQH+xDMrWcSiAqiHquzxre1kilRibM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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