SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '31a77c70c2fd0b1215c685b4de4d327dd09d06fe6719f7591b4868622c977247' 
  AND token = 'YSl3FpMDdJmjzF3yN6R0VUg3K6BfeYNSZnNoPivn33w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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