SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87391090af1eccf08f907760138340590f6a82c9b9d5f8f868984eb3a97565e6' 
  AND token = 'msyk1yhMFlL4omtPxki3bteCNlLm9uFiLQjttbq0NA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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