SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdd9519b689600212f0aba46f9ef0750b838c4bfa0fc84a63855917fae211e58' 
  AND token = 'NkiUQ1pO/zmCH8YKlcrJ+HGgTmles8le/dwgTyD3OvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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