SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c0fa5649060fd7ac9716e0745fd6995cbad333f248812a5a21091985400838b' 
  AND token = 'UQ8y+//l00cQ5y7Q9Jb6cmQXBqNtny6+ynuUEe5zEn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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