SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '488008298ffd63d12a988278629ecfd9441525214bf37c62c942ad025c676738' 
  AND token = 'xKzef38EX/cuO3AynVXHfPBpPFYiIEZ5UE6lpN81gtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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