SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f68bf1306611e72d06ec9d39b69368e1343fcc7a7096eb4927c69c0215450f6f' 
  AND token = 'vzkIeIbmGAOv/VwcTVUe/XlQyEEK8V3d/nWP9+9OKmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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