SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d80c835cc29a5574163e2663bb1120fde48c1dec84d90db0318077d51177303' 
  AND token = 'C3SC1GDkHnNHVEotX5j5CJlKIisFk7sgLAbhTanFyCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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