SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d1639dfb615b140ee8da38e23982ecb79521fedba2c08120c45a0565a3cdb14' 
  AND token = 'r+fjNUsEvXeYyCmknpIJZDN7WVxe/BF75XKvNdPLdMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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