SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '97f2b52b7b8707250cfd23289eb23f98302416203582bce87f3c7b26365a5bbb' 
  AND token = 'KaIJC/7S5XcThDniOLs4FFir66iMtbvyrROF0kpKkjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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