SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c5aaf7f63694025a304df03d0ab70c38e75938f520a890a1a857411db41208e' 
  AND token = '/X3DXUvEymhyYmBQJGQWPt4fpFx/nu5vAguqTiTi/Iw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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