SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5c3277268705f5af7444a401c236eba959ce324e572890f7b656997e99556b7' 
  AND token = 'tuqjVj/+ymBa7alBiWURH4dcMA79CLa5N6thzvWnaaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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