SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9946838642dc81b496e5b304b8981338596e7fab8bb3bf32dcf8904a7f2dd7b2' 
  AND token = 'WKdDPGKl7hJLhi+iIuGhXJTu850QBUut8OV+1kq8aEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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