SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78c57e1955599eca2b671f015354221e9ddf1754ed80bbdb2ad2a837172af9d5' 
  AND token = 'KJQOwLm4Agsl+v0XZki2MCq6B7aTh/jKyJ4dOjVp7hM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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