SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df68f652d476bdf9ed54b8dd9f912f9de3446fe726f418f956870f5453de4be8' 
  AND token = 'm6QhlxgattOXPX+A69LACtpzg/quYYzphgUTPC8H6G8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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