SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffe0e58c930fefe2661400f85627f5afae367574ff51cd7daa6883ac5c26c402' 
  AND token = 'QTTDLb/4Hpx+vzhbbJtk3Lz8YqS57mw9bhqAlwrGeRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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