SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e90dba96a04771a8fb68f5e2b7e793884062f2329932a61d1b1ed2c1daea75c8' 
  AND token = 'FJ/fvk9EvCqRV/WxS1qh5kb6C9hjjvbcxw5V9gjulM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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