SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcb725c70f1c4927bd4aecb4ed4ee5a0976daf3e38543d09cb25fc9669b9bf72' 
  AND token = 'Jz7N2X02UZiVRkhfMgHh/MwmdiWZoJF+UXQPx8zVYf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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