SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a0689346314751a860f76cfb29f1f8c7c8e57f079edaabd94501e2892835a2c0' 
  AND token = 'u9JFIUS+eFw/9PQ4ckkGr2nPUyB2dhDX3hK/5Iqukz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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