SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db8b3e9151b334bd3069edc05dfcb0b2d3e178999d5fb519d7e80861e0d3cb38' 
  AND token = '9nETrxyJqhyUUp21dmU06CrWjwhL8Kv/DkGnle5f8iA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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