SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2321566f31a041511f19af544a4c4453005c9972eccb4e6431f3aea2c2aee14d' 
  AND token = 'NdBxZpanEM3Qplyn9+rFLxQ8+z2JY6qsF8N7dlHZObs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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