SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '93678dd3ef77eb85378eb98355f2d96cb12515447fbbfef469326c340eeb7b75' 
  AND token = 'pwt+njeIlbHfs8adbkd3dt//PVIb8bWkRdSdZ/ItWec=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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