SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7757140fe35b1b8bb0fcfa45f47c9f5bda8d3625f589921ede7ed13dfd5ea424' 
  AND token = 'Rm6GC9SpcLgJSuoZZ/4tv2NPYpg3xQStg5BhbFF0oFw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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