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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec7676afe84a910316366e5dcdd3a37a0eb48c92fd04559f9bbc5d2ce67f0f48' 
  AND token = 'uHtwZL3D4so4vn8MBJE1KhUDmv5+1bvQ0d0c0JpI6Ps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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