SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e262a753eb5bef0f1dd439b573b17efefcad508f761263a3d63a6493024a95a0' 
  AND token = 'F+8//VZ/ihaGeFD93zAXWKZgk+uVXJpvZ5h3KkKcOBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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