SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6423472ba10a62b89abfc9c9fbd7efec1bc366f42f5266e8d2ff35264d2828a7' 
  AND token = 'N8TBA3V/tsoz+dHCZO9UdI+zgwLbj5X3Xcncxgpupa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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