SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2579ca68f39ff35ae67b563f9ae684da72214257e31f19f024892441edcb9840' 
  AND token = '6dXKGgWrgp0HRGLaf//sRvW+j3iJVsKlFype2433hKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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