SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b552d3c950548734ee80b738ad9ee864c4984c54781904ac468a85affd197e1' 
  AND token = '/E3a7PnEQoaoAqirSYxUtX576mTiV6ZUiYlAkzwHTAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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