SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f98426e8979b87480ca5160f3c0668e298dbaf85a47d2d154a483b54e01a3d3' 
  AND token = 'idkNhVU5kUdm8D45eT4QDXqDoQxIwL7OWIzDCuypcBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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