SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '855560972170d1179985e814fdf5b57e4a9fe33f5fd14ea7877f5ac3436c8baf' 
  AND token = 'UJfOca6hZ2/xHwNPi9MB6bNe3n0RgHmmV+czM1KY/4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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