SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac7b069b617795b52da20c5adfb2eed42a6d6c6760dc34cacced8ed21f049689' 
  AND token = 'c7J0aD95vKQaWltwpiNodaFLaZayBsREmRN5+ylxzMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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