SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e397e39a87699f5954d203c967c03c5657a06809da6c755153f6cf67f1b2347' 
  AND token = '1kitsB3BDmoXPCilBLVc0N/lRkHHLvXHQeHEqX3CVxE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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