SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '311fc494c82f5b49c10c10adcd9a03f203dd3c40709f27f6a8603a2f72f759f8' 
  AND token = 'Tg+sIsUKl1i7vJFK7VOA50sUUvMWgLqam5JcThkVAVc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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