SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7942a20823113d47becc5d5d0243eb48704c79fee399d48b63669975b6705b1b' 
  AND token = '7imYG46xDtVdtGKBwVJcf5GKhedeGuiKWaZbRZSzzW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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