SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c0f6542f8981f2d54d58a8bc2c1beb666d7f9654928c986234715eb52f91861' 
  AND token = 'O/aqrar/WSQhAQUzupzn5UmV311HO9xUk2eWHdvHkcQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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