SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79db3b0fa367988bf9e1918a3a3644aba9605a285027fa562e42dd5a8f2ae698' 
  AND token = '69VAYaFRQid+gZBXtFug7uIojHzdLEvjrXEAE7vq8nU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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