SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8d3da33343292eee21b37153d272c1623e937a9ce06a9536cbd76ec29b52c09' 
  AND token = 'cgGlMuLP5OOZ08QOt2VOsIy7AwK2eVDHJTpGe3mra3E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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