SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15bc00934d46dc44d736da35f3e4efe3b9bfeefc4361cbc440a483eee3012cd2' 
  AND token = 'Wj3ZcZbKPH6zr3u5CiX5jzC8DuVpNuFjHixmdsW+vEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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