SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7838809f0d0a1f7f36134203f3bcb914f94092be380429d1d120be7d37d0f388' 
  AND token = 'TDK3qzlKgqBKErt6BPYvsHUI7jYhz6kHfbE4+sZ+PDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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