SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a17aceae5f1895cadad5b6597a6db61bcef0ac28aef37557eec46bc669c5f262' 
  AND token = 'fxVvInfQHUxUMh/6Xx5BO9AAct2bf82gaMu0AJ+r3e0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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