SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6d0754c8f6cbc9d500f5fb38f49fb74ea6f0ed66bd80a10fcfcd7d81e76b9cb' 
  AND token = 'UMjqj+TO7yBfx39nv+uYK4dCnQd+MN/kaxoVDYSZdjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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