SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15f52097e959859132a08a68bb9b00afd88b4220011a59c1fdc205bd6d31ad0f' 
  AND token = 'QDlFQHdatSX9oTzkr+Nxe5yalEj0S6w3uhIchyPfyHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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