SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4bb78ca850321b7bf99dd35097d619846aee1a1d2eafeada92e83debe960bde' 
  AND token = 'LSIvUeVy2ooBku7FJZJoCb4ipnkP6GP3thdQxDXfrSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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