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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38f21ff567e89292df89838fe619794fd20d469f2e2c0802b32f89d7fe490eb2' 
  AND token = '2uUtxdNqCjTKbiWYM1cFnx9YaaDW7EwENJe196nMA34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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