SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eee1f7b18bb8ecfbb04f46c223eb796dc3cdb6ad85524264b8af47529a624994' 
  AND token = '4V8S/tpzGD9ToZwd0pqVz57pziPATFr+tKCg6CqWRh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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