SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4aa38656630ff565ebfb6bb0d29d6dc5e337213f979307b7afed807c91ad2fe' 
  AND token = '3Hu2GTPGY4/r9E4MQIz2hCSVPCZtJZYKXC/xi2/MwWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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