SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '920b8172669d181e76214456f448f0233a827c2c26cf482dc58e6cff4316fc40' 
  AND token = 'l/yiwAirOUFRamJqmEsNshi1herGZFzfr2FvkFlq/po=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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