SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8cff81d9b3adda236adf5661e5317d81c67f0f0c46fdddfb40dc028c45db1cd' 
  AND token = '3phjgtwPD0sPzE2VqQAN8N21JZwwtN8uomTNpUEsCuw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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