SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7befc00bdac3206b5b029510a6b1b60c7814d440a4f9230a2639690786489b34' 
  AND token = '9wn80NFUs/HRocz92eQt9vpgonTNGOUfceOr0zTeNAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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