SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '542fcb4f317c423834e66f830a80ae9251da12a9d219b69f617d089ac1083592' 
  AND token = 'TWYhKKfTRjzuC+zxzIFRgPq8xQbEN+WSDCvVr0fnLvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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