SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b58d19eda45414f608d1a5439d3510a3159c08b13c3c28d74aa80fed49535bf' 
  AND token = '5JJCkSJj3eCVndyEQfeOW0O/i3jHibEGblmzxt5eQYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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