SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b8dfc05dc08727eacb469c8013aa3eb54cd6691317e3e76d3373d55661b7783' 
  AND token = 'fy+HJZKLWHytOmjzlitMdhFccMvXLAJ8yt5l9Uonrug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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