SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bc6ee647de0295cee686635853d3649a6b79b6f25a7242fe38136beff9f80f4' 
  AND token = 'BuFfvaWnxnE9mUUVZPTMIByLiwv2psivMrOKQtp90ak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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