SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a628408aee7aee198fd5d8bb682faff0036ab1589b0eef43a943d2be965bba48' 
  AND token = '1WGY2VOxxjWaIyc3tDv5vNXeBeEiFAHXJHXv0Mfq6Tc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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