SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9cc256fdbb782ab7f91491378700739b9bf447d83bd965ec6fa64238d458290' 
  AND token = 'IukJCHnmkiMw4a7yumBHLYSFUnlQ20KXj0sn5DMWtDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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