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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b965b39a4ecfd6e2b800ae1b17eeadf775ccf9e34c5b860ce9bfcc8e5a8fe43' 
  AND token = 'Mvk8ztI8eE+gM+Zh4pt9nS9b5sDP5AKuZ+CD5vq7iF8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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