SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c244231d8381593574dbf0712a83c7802bee494d6dd8fd81f2bb4a00772f55d6' 
  AND token = 'qJCdma7XeFoLEx3PXzENgsOtEeFOrxyyQyoYc8gxc1c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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