SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3243bb317ce18dd2496313ca9dfd61f1748f51d08d8027232fd0b7331b55bc23' 
  AND token = 'G892PAgIJ4aV6GNnHTcAYwMUJG6+IwOQlC8lkBIovqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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