SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52c7cb28a901f950fb6fe753cbb7d264edd033bfefa02403c2e1fa239fab2b82' 
  AND token = 'aPgOem1Dfehkyf/5tyxzoIo+AEweK5tqfDgTSUoFF+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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