SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbd6a003acd1e38e37cc24f14e8d64a41c1bd57b89b246c3b37197478d9fe41f' 
  AND token = 'EKxlAe9ygPOAqWCb5GkJHmfHBYPrw8R5qj+Mlew7lr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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