SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6ce5f0fd79d0956e8bbde129f7d2168f524ad0d305edc79b92b4a3403758b52' 
  AND token = 'BkY6YdMrSrn8N/ENd+v4XGTkIWzTQmjSKf8oAgDb2E8=' 
  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"
    }
  }
}