SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '312c6f2f144fa39a708254ade96c6580690664173a7ccbba220199a448d04a2c' 
  AND token = '4QaPXriTD1qfi0xrVqQBgLhMp0LPE47s9znpCMKWrhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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