SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ddfacaf383acaf6c844345d9e79dc8212841671487106f6dad695699ad2a5f9' 
  AND token = 'NUqSk8YAm7QFHOmyS8NsZHPSkB9MOl+fgGAYfGn4/6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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