Sandbox

SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '18ff759a7b70301b31e782a4dea02e77d052395a3203bd62e46253307245da51' 
  AND token = 'CZDXVrstIb+iKf9zrvFSJ/LXAsn0bRpNEwAFcWfIzAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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