SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00d4eb0be179741da06bafc15a29673f892c4e3988cf7e343f1420448bca13b6' 
  AND token = 'kOkZDISgxmpWB1gu1xhooS458sr9HrEvjvOYINWBzQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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