SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '423c2c8f12a2feac948dd68221c2474ca816f9758e9d80ffedccb32d7d638a53' 
  AND token = '4MJb+WmP+UWNVgqqGPGmLiRQI6Lv2CTuLDoaHWsXVKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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