SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3ab52c102f08a5948c75ddbb9982de1f145c83ac89a82528e2779d5bfee185a8' 
  AND token = 'gzfOKNfcV5vuuZqxtOtfiK00fifPPvZKtHwCf5jTgTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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