SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b75e2eebcd223ddeba21c887fa970a0b31235620a03fbfb1b62757706cf40952' 
  AND token = 'HGyPxgoQn/qTmvAFqEZAnJRw9HTfQFQUfGc3IZZonzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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