SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2e670e9cb41968d867fa18b8c02f826be20989ae936b98c9fed70846b2523cc' 
  AND token = 'ungN/vhySC9GjmBnqgVfjE0v6Ms6Qpmh8/VEB+RwFsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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