SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5553cc7bd49efd9ad0ee0484ceae14a5f950ac72f20f460e9294635e7f62a269' 
  AND token = 'OrkWwWVG97uBOl1StREXIowIqGSoDQkc6etwGivpXDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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