SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd2f1e3b7f107f8cf24531643beb8404732a967acfc1e87bfdad6a01581a887b' 
  AND token = 'NIpbEJbjokeIx+ClRD50cyZZy5b0niIx78qmEJnwRGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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