SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '484dbcb3444d63f3cf677ca05880fcf0613187728809d3d3e82126890f7c7c67' 
  AND token = 'K+uvSyMvolOujXg+7lTbzQpS53uftwXeg8sSvkHPFiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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