SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cb4fa21fe7af5af19bebfd65747ad4b3dfc74dd0580700566c25f842da0c238' 
  AND token = 'aCM9DCrX4eo1SszzP/882dvqhmMXPG2O33nShk1eW3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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