SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '41dcf18c948e8e4bdc0703a735864abe5662da40549a35256e78cf8a9ec5a49d' 
  AND token = 'qaBo9U99UDgaYzQUMGYLihc1hDU8My/vssIOifJlT+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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