SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a20358de9e426c8f51f5f310e97704cd6b48ee4e078f85c76cfbab7cb7581a1' 
  AND token = 'S8JmHRYbHjYVBs9rquzqQtLz/ZN83kRKsWB57ZQiWAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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