SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8e83603db64cf932a531261d9c26991e23005e3b86ba213deb12d9cc47b5801' 
  AND token = 'qO61gBvYY+1kGwgC4hqCRq4tlF7ed92ebxCHiyfWWdI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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