SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f47472e78cd23e44068593890af2cf2d3666820ba718286020ac6d4a9e4c0ee' 
  AND token = 'bCy9g9EH88lF9AWiem4lQPhq67huFqnjFwFggPXrbUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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