SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c0e201555f7e46398755be2df38e99e661aea8518c0376eaa6bb9fa35b7a718' 
  AND token = '8GeFLPibHKyeYuFqOFiU4MsUHW/Vt77wlxhwKvqFv2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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