SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0961d3fa948594b9a18e1cba21f9c2e6d58c3b64e57e531109a5bffd508baaae' 
  AND token = 'an/wg2FWCn41c3Q1aN2SAY7nhiAjxPWSQvkuMmjGQn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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