SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8fd7f76be4cbd122b471b483d313af9f7d14bcbad529f5175cfb5733bfbe9af' 
  AND token = 'iOFXo2Kdw//Ka0mOXTiztYzhK9rpuhCqWVOD2sYNMwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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