SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9db40bffeb540aa6af34d579d69eb84f96b945269875b1c9c0979f6f8864c1b9' 
  AND token = '/ZosGwBuq/QH61EhxmgWSOycRTznitGLsk+7DHu4ETI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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