SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '188bd6049642408c5c294fdeec7ca0da4a3024d946bdeabb3395541dd3ba5dfb' 
  AND token = 'b8SRiJqZOXu8CEUXQfmrKfYHISgFLhvcijRCan6fMjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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