SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b67ac1a7d826a50bd46f394eee9bb6e87e0af915cc8700610952cbbdd48bb81e' 
  AND token = 'RgWpRBtNqK93ZATsZSQfHRouV6NcDrk0TUpYJ4BSPFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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