SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de5678b5b6de97705ef188d7589243768652f127b70fad44e4cb0106ed08c9c6' 
  AND token = '3rHQFkQGUAbnuoYsvMFZji1znPo6DhchHyNw3xYMu4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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