SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '778826a26eb8e3588f703cf46b47e1f193893f2a9f576edde7197ba0eb2d4037' 
  AND token = 'mxMQhdsgowGb2v5tbrYoQp0f9sZe6MrZGtwnSAdQCXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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