SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff73d4bb07df1638534a51bab80fc23d5f600102a73e5716e2d2601220be9cc7' 
  AND token = '3Jst42xPn9+v/8AbsP6Y3jGyiBVoW8n72qHvong/CKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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