SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fafb9a17bbea069e3cca45b5d9731aa141071da847d59d66685816bd1eb90c4f' 
  AND token = '4J4b8uimgPK33A9Iup3psYTw9JwewZnDzoCvgP5gg3o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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