SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a7dc0d8f2147cb7f9fdf407adafb99187d86dc84f4946a2d440a75dea281f94' 
  AND token = 'yjGDCZiWaXlaqTPhyzz8gLiBfroIjVSDAWJwk7ktEhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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