SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '234e84bfdca46dd8334612f261671ce98abf3c0d46d71da2b172d05e07a58ab2' 
  AND token = 'Zbaa8DNRsuoUaexVVTmQ9QUINT1d3kvnYYMySwBpAoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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