SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e19a817dccfd081eb72e7cdad5929ec76eda178ab3a9661b4508ef47c41b2629' 
  AND token = 'UTYYnIOksiJcibiyjrCSbsiW5xgxiMwyt8hrByO/gYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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