SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57888da33bda37527ec90184a44db8d512c424826fc743201fa2dff3474c48e8' 
  AND token = '4oyY/8i9bML6CM0PlShyAfFMyIOLWu7BWLyWGOc+7AI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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