SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b369860c6d29a00e35984d9101b768c6ce62ad55d23aa7189a778f43dc1ff5c' 
  AND token = 'T5WUlgVkIbALygmD9o/j5anfOuTDRcqxY2KlkIGLJ/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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