SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '35d755a499f2e371d3ec5ff204bb79cfbf38dd26dd74461d163644669c9ca9e6' 
  AND token = 'SFlQ3QgnagI19Tjr5pRGASMe7DArYqpbe/7vha+5uIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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