SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55e5b28bddd81b7756aa6d40276aab4d4076391cfdd86b8040d2d2480681e29d' 
  AND token = 'agXVIf08hfMTJqtlZPZ+/qfbF+HovCGMTvJfWIEK7PA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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