SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3eb85a1bbda44027b170fea698cb23c7df27881605780cde8469f573eca39db0' 
  AND token = '192ZQfMyNer3r7x6rThDFvS9Xt4t6vWopoXYeloV+w0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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