SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57cb48539a9f9654c56dec315137121cf3405c0e21f6081166c1685a4c27a46c' 
  AND token = '8NrV86RkR6G9nhRpGrLzVcl4fZCJdmqLOZxAhw9L5b0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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