SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81abd390302f02e24b67709687ccf1efd733e610343d18482dee34b820c09a60' 
  AND token = 'FtYqzoHd727xIbkAiPncAblXqQu7DNAVZsTfuvFkHho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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