SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '33d92844c8b4af05189235e739557a7f92483eff1fd7a297823eb0bd9830afe4' 
  AND token = 'roB0ugsO+/ll59RdKHGpAmsnOLD2p6Qw71mCLsJwwnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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