SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8ab81c428cb4b78526f9eae6568d3e55ba6cb64a5631c7d28bd760889b3c808' 
  AND token = 'YD5eJI4UpdGJxb9XPmxncdiOeQYqDcXcamKDcMh9yWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}