SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85b67a85d3f370af29a4647a966e5a31697ffc25ff34314aa92d149ec462dc7c' 
  AND token = 'N6RZyOv6JxdmIt2b/ASlTs73ssha6WBGQ0AxXnSjGQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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