SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '863f03971910349f8cdedef193c23e1562561da88aafc091d8fbf88975b0c8cc' 
  AND token = 'CJBPtNceW/fUMqfSBqETELhF6py861IEQ2W6bo2YBGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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