SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9929c46d983cb48bf94817640b8b64721dcc8fdf0767799a98376f7c1825d488' 
  AND token = 'sl3fFQmVAbirPuZxTYoYyU9HDOArgSWnnv3QZBAdzJU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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