SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f91f142afc6eeea27ea62359668629771ed63c9fa6d8fa9ce802d2875d013d9' 
  AND token = 'vH6E/k79okns/OF2KyAFT6K31JmeibY4ddRAJkYpwss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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