SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0821b5951b317fdd085aefdfba633d4ad6d428f1e529158f42e46412873cd8d' 
  AND token = 'sLqyn4hdAKszSVPZOCoGH758UNhFOYjATzXtvszhfrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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