SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c1e6d6cac4e685fbf2f2b7431a6bf993d5536d9b80bc156af3cfc80fb5e37fe' 
  AND token = 'DbJJ7XwZ/Xh4LLsfn+moZrxcjazmC2FFuuj+GNo0dD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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