SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5af35b9a47192e0234e112391a4554d349af3190da8634391f6c2d82471ee7c' 
  AND token = 'pRo4WoqBGIJzWY3kAyVznAfH2lZBLOfI6F53xaS2MEk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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