SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec698aa51216bf9c7063497a2121bce17d7df6b57427f550abc2edf96e205bd3' 
  AND token = 'U0IxbR7HtKUfYkDsBE1eW/LBIabLjYeUaSjXzz9j9Zk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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