SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c57cdb416e03deb906fadda89cf43ab92dcc0e095a16339b157c4e365d4ff1ee' 
  AND token = 'lMjuaMCyfofBe5rIApiuDn8kz3MEeHnsNOkJdq4vFCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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