SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5420fc058204534e5626ebb1293409b5df22de70b593fe08e960c60d475df14' 
  AND token = 'uIVUhkPoehVs3SRvnQrSq9822shkYDRh6aiBMXgteEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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