SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b982cfcc037dbbe634cd4ec37ebd2becf91dfc7126e7a47a7eb585b8be8b089' 
  AND token = 'WPxD9kQjTS+c6VbxVCH2YPsmvk4RKGWmJ8Xp+Z/Ihfo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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