SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42ce4d57261a3b0daddedb0697963bdfa798dadc13934fd3743d7f7ec83456b1' 
  AND token = '5ETqAT6R94vo3zdSBtLz9krojC1W7AtQfZqejmZYoMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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