SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f68f3238a521ff7bab50eb6971a7293bb17986b9bf3413417973d41c9ae933cb' 
  AND token = 'mYKajEvF9dOyPog1rdmzsL7lJhwqy0YHi3kYFuUHJOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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