SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6576435beeb1bf5399e6234be2bfe8883231bd64a6fd11b21df4ccffab981f52' 
  AND token = 'XzcbsDWgie4CLYs7a/PuzTGP2VXuXyk1zCl9LSfV4mA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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