SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '601e3dd5212572494ea4ece2d794ec3d124398369769237fb490e245a8b297da' 
  AND token = 'xrTG+0hR/2JVF/zlmqnq944nYO/bvhYxjrzKhm8pJeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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