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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84de5581c5f2465732f9d5cbd14e3f44a541e4ea019e8a4d83484dacc5a16938' 
  AND token = 'hTyoWtOtWmCHsvshR3gFv7BlAQDx5hRGvZ4Hawy+k7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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