SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f39e3bdae38cf05bfff0318b9505726f17cf10f98ff0799b7db5d671b629f0cd' 
  AND token = '3PpXw+/FyOvqGUqrk9burjXZ2xpYQBpoFltmB/551lI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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