SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91dae926cd58afaf540370e7f6865dddee949addda3f25198dcfc6b4eda3601c' 
  AND token = 'SeqQBrHi6VdqpoHTkarCFRF20sd0QNavoq4KgFJvbdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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