SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bddc9aff67ad467e734fee7facdc2e3eafc1757a4d09f57b9c8151bc2fbf7ad' 
  AND token = 'sFukS5MYaAtv/gvyIKeWn0tdAtwCuHcUpa0MIqrniIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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