SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac1e0e2cb5e5c28f7737b056960a0986b7f1f1eaae081c1d0fe21bda78dc2128' 
  AND token = 'jKBgXM+pg/xTQ3ItuZ0A/MbFoKoDnWZrGmhP+eDrfzw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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