SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '815b6385e4cb2b3e5dd00e20465e2b25c5f17341a0f3778f6a3df2098709a8aa' 
  AND token = 'h+sQHZzOwWS7gWw84TDwgmLIqSydlhDj3OBZ3B/5Ajs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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