SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '270af4a7e8117ebddf8f3c4eb8353a19abad8062517ac304589b50f64735ad5d' 
  AND token = 'kp8DxGLyhvAKhSEYjB6F1/jtS2UmzUZqkfe7a0AoaIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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