SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7cce97317e689a88caf64d7169154a8be3f74f7676f8fc4d2de80e2ec468e8f3' 
  AND token = '5xZ13Z2lJ71xPdfSwQ4wPwbF3yN/Gb0XrFtWJICpOxU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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