SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6599285a7b5d50e4f99f85a6bed591f861cce4c10023264ddd45f24c0ba28a74' 
  AND token = 'nrJ/qSOtwwBFgc2tN/C+v5OgiLy/HLYLAC7zfB9tZp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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