SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd52849841dfafab0f7ef51b521103a540d33b2feeb839487374976bb0a874593' 
  AND token = 'VKfjaSZg0LmBNS7j5ygdhaQkd6GnDmo5IJVB3+N/BTA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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