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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fc8aed078f5397f860bee4413178ab8cd9e7ad736aedf67bdcf94ad0666df91' 
  AND token = '0ZBJt1bcKQj7cxUeqE4ayiPftvQQJGLMGj9dgiaB2Wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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