SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac0635d4c629f60ba32fe27b4f9504deb089543ffb1244b7159c37145ca15118' 
  AND token = 'FOsnNJiigcEAMw8EJCCIu+bsKLwNZUT0YvuDkC2NV9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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