SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f3f96d2666d223e2937b487117a936fe9992f9005a2562f757ab27d4134b1c4' 
  AND token = 'KSy8wuOr4BdMBylnQzDxFBfGgWaCIR41v1lL9PYHi9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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