SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd76e1d9a8be4904415136815fa02c02a4555d0930f2decbddcea70b8bccd7034' 
  AND token = 'qqZR20oInJu6DKhYRAkUiUX7SrNl/emQoY7JbfOIAsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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