SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '273f3a4eedbc546a7ead72973806fb2d79c3c63845149c427f544ddfe71af6ad' 
  AND token = 'AjKdR+ZluJ1S1YFBXz8OJXO1Bm0cBt3Vu3+k4EyhmqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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