SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a34c1644af49cf886499e332bc6c161f5bdfab41df437021ebfe69afda7b5ab' 
  AND token = 'my0RYXmoqMwYw9eJHxi4YRbdRg9skUz52qp7nsdm34M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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