SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb8204bd36b04bcb00f4a7916ecf8c49fbd18278457f57b22110f85c229016d2' 
  AND token = 'JoEw5MPE1G9kzCXZeeuZNk+DzwZBZnd8FVug3vRjrAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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