SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '793616200240367bad8fbecc33b8ffebe54cb0273344a52c5f4f7a4dad407cc0' 
  AND token = '7v6xw8fpLp5ntod3AwLqAhuJCXbqgMCbVek1KOkCj1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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