SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b18e586aa7eaf8fbcd08cbd6587166f94a02e4d79106635b74435776a7ba2269' 
  AND token = 'VnCwhzAjEn5J+nkZOJqHh5ETICqh8IoO8GZx9ZSnGrs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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