SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78ee390ccf634f2ed5b68055bc2c2bbf83bbe7ec7ee408cce9b68223b5af903b' 
  AND token = 'GXPDwRoYg1eURK87REdJMwj+Ws9ZoLHLtNgcvltIXjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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