SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99fea8866dc860300888a654efe252106c58b0989c7697ab9b2501176a6e9f91' 
  AND token = 'PjHoUtssBf5v9Eg/srWFqTMkJOsj8UKbOm21gAYwiNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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