SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92d450bff8753caee75a0239c53d58bc8dc004823d5dd5c60735afa40ed9ed56' 
  AND token = 'mFcwNZKAugLbx+uZKMCLFSfN6EfsI3oJH3J11eAinH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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