SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa9067ebf8cb10f88dcfcd4d80b28ea330644f7c9adb7bc8d784286878a7dedc' 
  AND token = 'Mou+rNIqtiR/4pbiGlFEzDwQvwnbHhbUWvXGUgHvz8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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