SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dccb12441a351e6658bada072eb7d8c94735abeef24d9d3f11faa332f296a495' 
  AND token = 'NtZSwqOYnwzB9hiveSiVJwTX+itJdeduuUPYi/9aOLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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