SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8c90204d7bfef040328efe3c7f76ccc9d83e071a2547b27517c2492e247118f' 
  AND token = 'i6gELQgUlYxWGqLkjq3t2BsDOK39pS+PRxUhiZgsFfc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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