SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ac8478d3858302a98d0ab20dd970f5cf09d14fb8632c88fa3f75e346aed07f8' 
  AND token = '7G/I/w2d9TgK9dOBSzx7Q2mKzjqyOvQ4vwN/UXxJm/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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