SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e089cf3dc0bdb030ca723493bc49b40f2874908a3254fefe566a081d742943d' 
  AND token = 'g+1iyVi4fbW34LarkC9DsqO72IEjvdMBrhuxjWBcfXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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