SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5668413e8e07b5afea4aa9a615e2e8c5f49a5f2ab7abcf579868f0f3ab2da8d' 
  AND token = 'GEzM5cOKnlWnHkOGQD7tKUYV8Da+UFANP0pDwWd8Djg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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