SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f58a6bb044d782611448c622ca66bd4920d0527236d5704a41f4fcba7b1a2a8' 
  AND token = 'yTtM8HfFlwyjQbrfm3j7Qh/fcVxPCHzeG/0ouV0YxoA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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