SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3f0942a8dd8e90063fea5d4b87f592b0554f6f8253c260cb15c919e766aa1a7' 
  AND token = 'dmjVuIxK+7ju3KxSiL0JxWnXbqbv1CXvCbhVkPyEAEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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