SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '412b136f22aaa5eb3095fbdfdc22bba044db8f1f5d5c6be7515795870d7f3b00' 
  AND token = 'KI7GxcShGrlcPDpfgKdvod7Aosh1SYXoAYTUT0jQEsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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