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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a55c20e3cceb86fe4cd94a132697d6dbc495bbc168db9ceb0bbd05527abcc3c' 
  AND token = '4BYZ9kvM3N0nrVkGRznpnqqCJ0hRbHy/vKWw7Oi2HTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}