SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '086c5cc76f0dadf0d0340387ff734e328ecf44ac559104df31ca4f3692d32ccb' 
  AND token = '8WS1lQYPhi1W1m4Ogu7g45J3zw4Grd0vfX5qUlC+cqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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