SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67f3a7e3decd492d914cf277dae04ae47137f29a69b444bb785a6c539e517af0' 
  AND token = 'WdidqZhduXGlK77ZzEwFBiIZtI22y6nMzI3QGDoqUeE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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